Appendix C: Estimates of Nonmedical Prescription Psychotherapeutic Drug Use in Earlier Years

C.1 Background

This appendix presents data on the estimated prevalence of nonmedical use of prescription psychotherapeutic drugs over the extended period from 1985 to 2004 based on the National Surveys on Drug Use and Health (NSDUHs). In that time period, the survey was conducted in 1985, 1988, and annually from 1990 to 2004. Prior to 2002, NSDUH was known as the National Household Survey on Drug Abuse (NHSDA). The estimates in this appendix are provided for three periods: 1985 to 1998 or 1994 to 1998¹; 1999 to 2001; and 2002 to 2004.

Major enhancements to NSDUH survey methods were introduced between 1998 and 1999 and between 2001 and 2002 (Office of Applied Studies [OAS], 2000b, 2003). In 1999, three changes were made to improve the accuracy of the survey estimates: (1) the mode of collecting data on drug use and other sensitive behaviors was changed from paper-and-pencil interviewing (PAPI) with self-administered answer sheets to audio computer-assisted self-interviewing (ACASI); (2) the sample size was expanded almost fourfold to nearly 70,000; and (3) the sample was redesigned to support the development of both State and national estimates.

In 2002, the survey name was changed, as stated above, and a $30 incentive for respondent participation also was initiated to increase response rates. In addition, the sample weighting procedures used population data from the 2000 decennial census, beginning with the 2002 survey. The 2000 and 2001 weighting procedures used population projections based on the 1990 census.

These methodological changes in 1999 and 2002 achieved their objectives of improving the survey's annual estimates for prevalence and other measures. In doing so, however, these changes also created discontinuities over which trends could not be assessed. Across the years immediately preceding and following these transitions, it was not possible to determine the extent to which any differences in observed prevalence were due to methodological changes or to actual changes in prevalence in the population.

Analysis of the impact of the new data collection procedures introduced in 1999, for example, showed significantly higher rates of use of some specific drugs among persons overall or in specific age groups. Rates of lifetime nonmedical use of prescription psychotherapeutic drugs were significantly higher in several drug classes and age groups with the new ACASI data collection procedure than with the previous PAPI procedure (Chromy, Davis, Packer, & Gfroerer, 2002).

The 2002 survey observed significant improvements in response rates beginning in January 2002, which probably reduced nonresponse bias in NSDUH. The higher response rates had been expected, based on an experiment conducted in 2001 that showed that incentives increased response rates with no significant impact on prevalence rates. However, the results of the 2002 survey showed increases in prevalence rates compared with 2001. Additional analyses of the 2002 data and the data from the 2001 experiment suggested that the incentive, and possibly the other survey changes, were associated with an increased reporting of substance use among survey respondents and not simply with increased response rates (OAS, 2003).

Because of the discontinuities associated with these transitions, analysis of trends in nonmedical prescription psychotherapeutic drug use and other indicators is limited to the years when data are comparable: 1985 to 1998, 1999 to 2001, and 2002 to 2004. No inferences about trends that bridge the methodological transition years should be made on the basis of the data presented here.²

Special consideration also should be given to the data for 2001. Although the data from 1999 to 2001 were collected using generally comparable methods, the 2001 survey differed from the 1999 and 2000 surveys in that it included (1) an embedded experiment to determine the effects of using an incentive to improve response rates and (2) steps to ensure better compliance with the intended survey protocol. Increases in substance use rates were found between 2000 and 2001. Analyses indicated that a portion of these increases might have reflected the effects of the methodological differences. Rates of substance use estimated from 2001 data collected before the incentive experiment and data from areas where the incentive was not used still showed increases from 2000 estimates, but the magnitude of the increase was somewhat smaller than that found with the complete 2001 data (OAS, 2002b).

C.2 Any Prescription Psychotherapeutic Drug

Long-term estimates of the prevalence of nonmedical use of any prescription psychotherapeutic drug are shown in Figure C.1 and in Table s C.1 and C.7. Among persons aged 12 or older, past year misuse of any prescription psychotherapeutic drug decreased from 6.2 percent in 1985 to 2.6 percent in 1998.

Trends by age group for the period from 1994 through 1998 indicate that the percentage of youths aged 12 to 17 misusing any prescription psychotherapeutic drug gradually increased from 3.7 percent in 1994 to 5.0 percent in 1997, then decreased to 3.7 percent in 1998. Among those aged 18 to 25, the rate of prescription drug misuse was 5.0 percent in 1994 and 6.4 percent in 1998, which was not a statistically significant difference. However, the rate in 1996 for young adults (6.7 percent) was significantly higher than that in 1994. Between 1999 and 2001, past year use of any psychotherapeutic drug increased significantly among persons in each age group; that was particularly true between 2000 and 2001. A portion of that increase may reflect the effects of the previously mentioned methodological changes between 2000 and 2001. Between 2002 and 2004, the rate of nonmedical use of any prescription psychotherapeutic drug did not change significantly for persons aged 12 or older or in any of the three age groups.

Figure C.1 Past Year Nonmedical Use of Any Prescription Psychotherapeutic Drug among Persons Aged 12 or Older, by Age Group: Percentages, 1985-2004

Figure C.1 D

Note: Estimates are not comparable from 1998 to 1999 or from 2001 to 2002; no conclusions should be drawn regarding trends over these breaks. Comparable disaggregations by age were not available for past year use for survey years 1985, 1988, and 1990-1993.
Source: SAMHSA, Office of Applied Studies, National Survey on Drug Use and Health, 1985-2004.

C.3 Pain Relievers

Misuse of pain relievers in the past year declined from 3.6 percent in 1985 to 1.9 percent in 1998 among the population aged 12 or older (Figure C.2 and Table C.2). Between 1994 and 1998, past year pain reliever misuse did not change significantly overall or for youths aged 12 to 17 and for adults aged 26 or older. For those aged 18 to 25, the rate increased from 3.5 percent in 1994 to 4.9 percent in 1996, but the rate in 1998 (4.4 percent) was not significantly different from that in 1994.

As with misuse of any prescription psychotherapeutic drug, nonmedical use of pain relievers increased from 1999 and 2000 to 2001 in each of the age groups; the rates were highest among young adults aged 18 to 25 (7.6 percent in 1999, 7.3 percent in 2000, and 9.6 percent in 2001 [Table C.8]). As noted previously, methodological changes between 2000 and 2001 may have contributed to these apparent increases. The prevalence of nonmedical use of pain relievers in the past year did not change significantly from 2002 to 2004.

Figure C.2 Past Year Nonmedical Use of Pain Relievers among Persons Aged 12 or Older, by Age Group: Percentages, 1985-2004

Figure C.2 D

C.4 Tranquilizers

Past year nonmedical use of tranquilizers in the population aged 12 or older declined from 3.2 percent in 1985 to 0.9 percent in 1998 (Figure C.3 and Table C.3). Trends by age group over the period from 1994 to 1998 (Table C.9) showed an overall decline in past year tranquilizer misuse among those aged 26 or older (from 1.1 to 0.6 percent).

Although there were no significant changes in rates between 1994 and 1998 for persons in the other two age groups, there were some significant changes within this 5-year period. Among youths aged 12 to 17, for example, the rate in 1997 (1.3 percent) was higher than that in 1994 (0.9 percent) and 1995 (0.6 percent). For young adults aged 18 to 25, there was a marginally significant (p = .049) increase in past year tranquilizer misuse between 1994 and 1995 (from 1.9 to 2.8 percent). However, the rate for this age group in 1994 (1.9 percent) was not significantly different from that in 1998 (2.7 percent).

Figure C.3 Past Year Nonmedical Use of Tranquilizers among Persons Aged 12 or Older, by Age Group: Percentages, 1985-2004

Figure C.3 D

Between 1999 and 2001, the rate of past year nonmedical use of tranquilizers increased overall and among persons aged 18 to 25 (from 3.1 to 4.2 percent) and among those aged 26 or older (from 0.9 to 1.2 percent) (Table C.9). However, as with other drugs, this increase may have reflected the effects of methodological changes between 2000 and 2001. From 2002 to 2004, there were no significant changes in the rate of past year tranquilizer misuse overall or for any of the three age groups.

C.5 Stimulants

Between 1985 and 1998, the rate of past year nonmedical use of prescription-type stimulants in the population aged 12 or older declined from 2.9 to 0.7 percent, with the change coming largely between 1985 and 1992 (Figure C.4 and Table C.4). In the three age groups, there were no statistically significant changes in the misuse of stimulants from 1994 to 1998, and none of the apparent changes within that time reached significance.

Figure C.4 Past Year Nonmedical Use of Stimulants among Persons Aged 12 or Older, by Age Group: Percentages, 1985-2004

Figure C.4 D

Note: Estimates are not comparable from 1998 to 1999 or from 2001 to 2002; no conclusions should be drawn regarding trends over these breaks. Comparable disaggregations by age were not available for past year use for survey years 1985, 1988, and 1990-1993. Estimates for stimulants in 1999-2004 include methamphetamine.
Source: SAMHSA, Office of Applied Studies, National Survey on Drug Use and Health, 1985-2004.

Between 1999 and 2001, past year nonmedical use of stimulants remained stable for persons aged 12 or older, youths aged 12 to 17, and adults aged 26 or older (Table C.10). Among young adults aged 18 to 25, the rate declined from 3.0 percent in 1999 to 2.4 percent in 2000, then increased to 3.4 percent in 2001. Between 2002 and 2004, the rate of stimulant misuse remained stable overall but declined from 2.6 to 2.0 among youths aged 12 to 17.

C.6 Methamphetamine

Questions about the most recent use of methamphetamine were added to the survey in 1999. Hence, it is possible to assess trends in past year methamphetamine prevalence from 1999 through 2001 and from 2002 through 2004 but not for earlier survey years.

As shown in Figure C.5 and in Table s C.5 and C.11, the rates of past year methamphetamine use remained stable overall between 1999 and 2001 and between 2002 and 2004. Within age groups, the rate increased from 1.2 percent in 2000 to 1.7 percent in 2001 among those aged 18 to 25, but there was no significant difference between the rate in 1999 (1.5 percent) and that in 2001. Between 2002 and 2004, past year methamphetamine use by youths aged 12 to 17 decreased from 0.9 to 0.6 percent.

Figure C.5 Past Year Nonmedical Use of Methamphetamine among Persons Aged 12 or Older, by Age Group: Percentages, 1999-2004

Figure C.5 D

Note: Estimates are not comparable from 2001 to 2002; no conclusions should be drawn regarding trends over this break.
Source: SAMHSA, Office of Applied Studies, National Survey on Drug Use and Health, 1999-2004.

C.7 Sedatives

Misuse of sedatives in the past year declined from 1.1 percent in 1985 to 0.2 percent in 1998 among the overall population aged 12 or older (Figure C.6 and Table C.6). Between 1994 and 1998, there was no significant change in the rate of sedative misuse overall or in any of the three age groups (Table C.12). The percentages of nonmedical sedative users also were stable between 1999 and 2001 and between 2002 and 2004; this pattern held overall and in each of the separate age groups.

Figure C.6 Past Year Nonmedical Use of Sedatives among Persons Aged 12 or Older, by Age Group: Percentages, 1985-2004

Figure C.6 D

C.8 Summary

Although NSDUH provides estimates of nonmedical prescription psychotherapeutic drug use rates in 1985, 1988, and annually from 1990 to 2004, it is not possible to assess long-term trends over that entire period because of methodological changes that disrupted the comparability of the data between 1998 and 1999 and between 2001 and 2002. In the earlier years between 1985 and 1998, however, estimates for the population aged 12 or older indicate that there were declines in past year nonmedical use of prescription psychotherapeutic drugs overall and in each of the four therapeutic drug classes. For this general population, there is little evidence of systematic change in rates from 1999 to 2001 or from 2002 to 2004. Some increases in rates of prescription psychotherapeutic drug misuse were observed between 2000 and 2001 within specific age groups, but a portion of these increases may have reflected methodological differences between the surveys in those years.

A distant glance at the graphs in this appendix might suggest that prescription psychotherapeutic drug misuse has increased substantially since 1985 and particularly since the 1990s. A closer look, however, indicates that the largest apparent changes in prevalence in the NSDUH data occurred between the gaps in the trends—over the periods when the survey data were not comparable. For this reason, the NSDUH data do not provide conclusive evidence of either a long-term increase or a decline in the rates of nonmedical use of any of the four types of prescription psychotherapeutic drugs.

Nevertheless, these limitations of the NSDUH data for studying long-term trends in prescription psychotherapeutic drug misuse do not minimize or negate the concerns cited in Chapter 1 about this problem. In particular, the improvements in estimation procedures over the years highlight a problem that may have existed for longer than previously suspected: As shown in the 2004 data, approximately 6 percent of individuals aged 12 or older misused prescription psychotherapeutic drugs in the past year. Among youths aged 12 to 17, the rate was 1 in 11 (approximately 9 percent); and among young adults aged 18 to 25, 1 in 7 (approximately 14 percent) was a past year nonmedical user of prescription psychotherapeutic drugs.

**Table C.1 Nonmedical Use of Any Prescription Psychotherapeutic Drug among Persons Aged 12 or Older: Percentages, 1985-2004**
Survey Year	Period of Nonmedical Use
Survey Year	Lifetime	Past Year	Past Month
NOTE: Any Prescription Psychotherapeutic Drug includes pain relievers, tranquilizers, stimulants, and sedatives. NOTE: Estimates for 1985 through 1993 have been adjusted for comparability with estimates for 1994 through 1998. Estimates were adjusted by formally modeling the effect of the new methodology, relative to the old methodology, using 1994 data. See Appendix E of the National Household Survey on Drug Abuse: Main Findings 1998 (OAS, 2000a) for information on the adjustment procedures. NOTE: Estimates for 1999 through 2004 have not been adjusted for comparability. See Appendix C of the Results from the 2004 National Survey on Drug Use and Health: National Findings (OAS, 2005b) for information on the comparability of the 1999 to 2004 estimates with pre-1999 estimates. Source: SAMHSA, Office of Applied Studies, National Survey on Drug Use and Health, 1985-2004.
1985	15.3	6.2	3.8
1988	11.2	4.6	2.1
1990	11.3	3.4	1.7
1991	11.9	3.6	1.9
1992	11.0	3.0	1.5
1993	10.5	3.1	1.5
1994	10.0	2.9	1.2
1995	10.1	2.9	1.2
1996	9.5	3.1	1.4
1997	9.1	2.8	1.2
1998	9.2	2.6	1.1
1999	15.4	4.2	1.8
2000	14.5	3.9	1.7
2001	16.0	4.9	2.1
2002	19.8	6.2	2.6
2003	20.1	6.3	2.7
2004	20.0	6.1	2.5

**Table C.2 Nonmedical Use of Prescription-Type Pain Relievers among Persons Aged 12 or Older: Percentages, 1985-2004**
Survey Year	Period of Nonmedical Use
Survey Year	Lifetime	Past Year	Past Month
NOTE: Estimates for 1985 through 1993 have been adjusted for comparability with estimates for 1994 through 1998. Estimates were adjusted by formally modeling the effect of the new methodology, relative to the old methodology, using 1994 data. See Appendix E of the National Household Survey on Drug Abuse: Main Findings 1998 (OAS, 2000a)) for information on the adjustment procedures. NOTE: Estimates for 1999 through 2004 have not been adjusted for comparability. See Appendix C of the Results from the 2004 National Survey on Drug Use and Health: National Findings (OAS, 2005b) for information on the comparability of the 1999 to 2004 estimates with pre-1999 estimates. Source: SAMHSA, Office of Applied Studies, National Survey on Drug Use and Health, 1985-2004.
1985	7.6	3.6	1.4
1988	5.8	2.7	0.7
1990	6.3	2.5	0.9
1991	6.8	2.5	0.8
1992	6.1	2.4	0.9
1993	6.4	2.2	0.8
1994	6.0	2.0	0.7
1995	6.1	1.9	0.6
1996	5.5	2.1	0.9
1997	4.9	1.9	0.7
1998	5.3	1.9	0.8
1999	9.0	3.0	1.2
2000	8.6	2.9	1.2
2001	9.8	3.7	1.6
2002	12.6	4.7	1.9
2003	13.1	4.9	2.0
2004	13.2	4.7	1.8

**Table C.3 Nonmedical Use of Prescription-Type Tranquilizers among Persons Aged 12 or Older: Percentages, 1985-2004**
Survey Year	Period of Nonmedical Use
Survey Year	Lifetime	Past Year	Past Month
NOTE: Estimates for 1985 through 1993 have been adjusted for comparability with estimates for 1994 through 1998. Estimates were adjusted by formally modeling the effect of the new methodology, relative to the old methodology, using 1994 data. See Appendix E of the National Household Survey on Drug Abuse: Main Findings 1998 (OAS, 2000a) for information on the adjustment procedures. NOTE: Estimates for 1999 through 2004 have not been adjusted for comparability. See Appendix C of the Results from the 2004 National Survey on Drug Use and Health: National Findings (2005b) for information on the comparability of the 1999 to 2004 estimates with pre-1999 estimates. Source: SAMHSA, Office of Applied Studies, National Survey on Drug Use and Health, 1985-2004.
1985	7.6	3.2	2.2
1988	4.4	2.1	1.3
1990	4.0	1.2	0.6
1991	5.1	1.5	1.1
1992	4.7	1.4	0.8
1993	4.2	1.1	0.6
1994	4.0	1.1	0.5
1995	3.9	1.0	0.4
1996	3.6	1.1	0.4
1997	3.2	1.0	0.4
1998	3.5	0.9	0.3
1999	6.3	1.2	0.5
2000	5.8	1.2	0.4
2001	6.2	1.6	0.6
2002	8.2	2.1	0.8
2003	8.5	2.1	0.8
2004	8.3	2.1	0.7

**Table C.4 Nonmedical Use of Prescription-Type Stimulants among Persons Aged 12 or Older: Percentages, 1985-2004**
Survey Year	Period of Nonmedical Use
Survey Year	Lifetime	Past Year	Past Month
NOTE: Estimates for 1985 through 1993 have been adjusted for comparability with estimates for 1994 through 1998. Estimates were adjusted by formally modeling the effect of the new methodology, relative to the old methodology, using 1994 data. See Appendix E of the National Household Survey on Drug Abuse: Main Findings 1998 (OAS, 2000a) for information on the adjustment procedures. NOTE: Estimates for 1999 through 2004 have not been adjusted for comparability. See Appendix C of the Results from the 2004 National Survey on Drug Use and Health: National Findings (OAS, 2005b) for information on the comparability of the 1999 to 2004 estimates with pre-1999 estimates. Source: SAMHSA, Office of Applied Studies, National Survey on Drug Use and Health, 1985-2004.
1985	7.3	2.9	1.8
1988	5.7	1.9	1.2
1990	5.5	1.2	0.6
1991	5.6	1.0	0.4
1992	5.0	0.7	0.3
1993	4.8	0.9	0.5
1994	4.6	0.7	0.3
1995	4.9	0.8	0.4
1996	4.7	0.9	0.4
1997	4.5	0.8	0.3
1998	4.4	0.7	0.3
1999	7.2	1.0	0.4
2000	6.6	0.9	0.4
2001	7.1	1.1	0.5
2002	9.0	1.4	0.5
2003	8.8	1.2	0.5
2004	8.3	1.2	0.5

**Table C.5 Nonmedical Use of Methamphetamine among Persons Aged 12 or Older: Percentages, 1999-2004**
Survey Year	Period of Nonmedical Use
Survey Year	Lifetime	Past Year	Past Month
NOTE: Prior to 1999, information collected on use of methamphetamine was limited. NOTE: Estimates for 1999 through 2004 have not been adjusted for comparability. See Appendix C of the Results from the 2004 National Survey on Drug Use and Health: National Findings (OAS, 2005b) for information on the comparability of the 1999 to 2004 estimates with pre-1999 estimates. Source: SAMHSA, Office of Applied Studies, National Survey on Drug Use and Health, 1999-2004.
1999	4.3	0.5	0.2
2000	4.0	0.5	0.2
2001	4.3	0.6	0.3
2002	5.3	0.7	0.3
2003	5.2	0.6	0.3
2004	4.9	0.6	0.2

**Table C.6 Nonmedical Use of Prescription-Type Sedatives among Persons Aged 12 or Older: Percentages, 1985-2004**
Survey Year	Period of Nonmedical Use
Survey Year	Lifetime	Past Year	Past Month
NOTE: Estimates for 1985 through 1993 have been adjusted for comparability with estimates for 1994 through 1998. Estimates were adjusted by formally modeling the effect of the new methodology, relative to the old methodology, using 1994 data. See Appendix E of the National Household Survey on Drug Abuse: Main Findings 1998 (OAS, 2000a)) for information on the adjustment procedures. NOTE: Estimates for 1999 through 2004 have not been adjusted for comparability. See Appendix C of the Results from the 2004 National Survey on Drug Use and Health: National Findings (OAS, 2005b) for information on the comparability of the 1999 to 2004 estimates with pre-1999 estimates. Source: SAMHSA, Office of Applied Studies, National Survey on Drug Use and Health, 1985-2004.
1985	4.8	1.1	0.5
1988	2.6	0.7	0.2
1990	2.8	0.5	0.2
1991	3.2	0.5	0.2
1992	2.6	0.4	0.2
1993	2.6	0.3	0.2
1994	2.6	0.4	0.1
1995	2.7	0.3	0.2
1996	2.3	0.3	0.1
1997	1.9	0.3	0.1
1998	2.1	0.2	0.1
1999	3.5	0.3	0.1
2000	3.2	0.3	0.1
2001	3.3	0.4	0.1
2002	4.2	0.4	0.2
2003	4.0	0.3	0.1
2004	4.1	0.3	0.1

**Table C.7 Nonmedical Use of Any Prescription Psychotherapeutic Drug in the Past Year among Persons Aged 12 or Older, by Age Group: Percentages, 1994-2004**
Survey Year	Age Group
Survey Year	12 or Older	12 to 17	18 to 25	26 or Older
NOTE: Any Prescription Psychotherapeutic Drug includes pain relievers, tranquilizers, stimulants, and sedatives. NOTE: Estimates for 1999 through 2004 have not been adjusted for comparability. See Appendix C of the Results from the 2004 National Survey on Drug Use and Health: National Findings (OAS, 2005b) for information on the comparability of the 1999 to 2004 estimates with pre-1999 estimates. Source: SAMHSA, Office of Applied Studies, National Survey on Drug Use and Health, 1994-2004.
1994	2.9	3.7	5.0	2.4
1995	2.9	3.9	6.5	2.2
1996	3.1	4.7	6.7	2.3
1997	2.8	5.0	5.8	2.0
1998	2.6	3.7	6.4	1.9
1999	4.2	7.1	9.9	2.8
2000	3.9	7.1	9.3	2.6
2001	4.9	7.9	12.1	3.3
2002	6.2	9.2	14.2	4.5
2003	6.3	9.2	14.5	4.5
2004	6.1	8.8	14.8	4.2

**Table C.8 Nonmedical Use of Prescription-Type Pain Relievers in the Past Year among Persons Aged 12 or Older, by Age Group: Percentages, 1994-2004**
Survey Year	Age Group
Survey Year	12 or Older	12 to 17	18 to 25	26 or Older
NOTE: Estimates for 1999 through 2004 have not been adjusted for comparability. See Appendix C of the Results from the 2004 National Survey on Drug Use and Health: National Findings (OAS, 2005b) for information on the comparability of the 1999 to 2004 estimates with pre-1999 estimates. Source: SAMHSA, Office of Applied Studies, National Survey on Drug Use and Health, 1994-2004.
1994	2.0	2.8	3.5	1.7
1995	1.9	3.0	4.2	1.4
1996	2.1	3.7	4.9	1.4
1997	1.9	3.6	3.8	1.4
1998	1.9	3.1	4.4	1.3
1999	3.0	5.5	7.6	1.9
2000	2.9	5.4	7.3	1.8
2001	3.7	6.4	9.6	2.3
2002	4.7	7.6	11.4	3.1
2003	4.9	7.7	12.0	3.3
2004	4.7	7.4	11.9	3.0

**Table C.9 Nonmedical Use of Prescription-Type Tranquilizers in the Past Year among Persons Aged 12 or Older, by Age Group: Percentages, 1994-2004**
Survey Year	Age Group
Survey Year	12 or Older	12 to 17	18 to 25	26 or Older
NOTE: Estimates for 1999 through 2004 have not been adjusted for comparability. See Appendix C of the Results from the 2004 National Survey on Drug Use and Health: National Findings (OAS, 2005b) for information on the comparability of the 1999 to 2004 estimates with pre-1999 estimates. Source: SAMHSA, Office of Applied Studies, National Survey on Drug Use and Health, 1994-2004.
1994	1.1	0.9	1.9	1.1
1995	1.0	0.6	2.8	0.8
1996	1.1	1.0	2.6	0.9
1997	1.0	1.3	2.5	0.7
1998	0.9	1.1	2.7	0.6
1999	1.2	1.6	3.1	0.9
2000	1.2	1.6	3.0	0.9
2001	1.6	1.7	4.2	1.2
2002	2.1	2.3	4.9	1.5
2003	2.1	2.3	5.3	1.5
2004	2.1	2.1	5.2	1.6

**Table C.10 Nonmedical Use of Prescription-Type Stimulants in the Past Year among Persons Aged 12 or Older, by Age Group: Percentages, 1994-2004**
Survey Year	Age Group
Survey Year	12 or Older	12 to 17	18 to 25	26 or Older
NOTE: Estimates for 1999 through 2004 have not been adjusted for comparability. See Appendix C of the Results from the 2004 National Survey on Drug Use and Health: National Findings (OAS, 2005b) for information on the comparability of the 1999 to 2004 estimates with pre-1999 estimates. Source: SAMHSA, Office of Applied Studies, National Survey on Drug Use and Health, 1994-2004.
1994	0.7	1.2	1.3	0.5
1995	0.8	1.5	2.0	0.5
1996	0.9	1.5	2.0	0.6
1997	0.8	1.7	1.5	0.5
1998	0.7	1.2	1.9	0.4
1999	1.0	2.1	3.0	0.6
2000	0.9	2.4	2.4	0.5
2001	1.1	2.2	3.4	0.6
2002	1.4	2.6	3.7	0.8
2003	1.2	2.3	3.5	0.6
2004	1.2	2.0	3.7	0.7

**Table C.11 Nonmedical Use of Methamphetamine in the Past Year among Persons Aged 12 or Older, by Age Group: Percentages, 1994-2004**
Survey Year	Age Group
Survey Year	12 or Older	12 to 17	18 to 25	26 or Older
NOTE: Estimates for 1999 through 2004 have not been adjusted for comparability. See Appendix C of the Results from the 2004 National Survey on Drug Use and Health: National Findings (OAS, 2005b) for information on the comparability of the 1999 to 2004 estimates with pre-1999 estimates. Source: SAMHSA, Office of Applied Studies, National Survey on Drug Use and Health, 1994-2004.
1999	0.5	0.7	1.5	0.3
2000	0.5	0.8	1.2	0.3
2001	0.6	0.8	1.7	0.4
2002	0.7	0.9	1.7	0.4
2003	0.6	0.7	1.6	0.4
2004	0.6	0.6	1.6	0.4

**Table C.12 Nonmedical Use of Prescription-Type Sedatives in the Past Year among Persons Aged 12 or Older, by Age Group: Percentages, 1994-2004**
Survey Year	Age Group
Survey Year	12 or Older	12 to 17	18 to 25	26 or Older
NOTE: Estimates for 1999 through 2004 have not been adjusted for comparability. See Appendix C of the Results from the 2004 National Survey on Drug Use and Health: National Findings (OAS, 2005b) for information on the comparability of the 1999 to 2004 estimates with pre-1999 estimates. Source: SAMHSA, Office of Applied Studies, National Survey on Drug Use and Health, 1994-2004.
1994	0.4	0.5	0.6	0.3
1995	0.3	0.5	0.5	0.3
1996	0.3	0.4	0.7	0.2
1997	0.3	0.4	0.6	0.2
1998	0.2	0.6	0.5	0.2
1999	0.3	0.5	0.6	0.2
2000	0.3	0.5	0.6	0.2
2001	0.4	0.3	0.6	0.3
2002	0.4	0.6	0.5	0.4
2003	0.3	0.5	0.5	0.3
2004	0.3	0.5	0.5	0.2

¹ For the earlier survey years, trends by age group are available only for 1994 to 1998.

² An earlier transition occurred in 1994, but in that case, the split-sample approach yielded a procedure for adjusting data from earlier surveys to make estimates from them comparable with the estimates from the surveys from 1994 through 1998.