Notation Pie sub ia at time t denotes the year-t specific predicted probability of substance use for State i, for age group a and is computed as the ratio of 2 quantities. The numerator is the sum of the cross product of the year-t specific population projections for block-group b, age group a, and gender by race/ethnicity domain d (N sub bad at time t) and the predicted probability of substance use for block-group b, age group a, and gender by race/ethnicity domain d (pi sub bad at time t), summed over all 8 gender by race/ethnicity domains and all the block-groups in State i. The denominator is the sum of the year-t specific population projections for block-group b, age group a, and gender by race/ethnicity domain d (N sub bad at time t), summed over all 8 gender by race/ethnicity domains and all the block-groups in State i.