"During the 1990s, the annual prevalence of marijuana use tripled among 8th graders (from 6% in 1991 to 18% in 1996), more than doubled among 10th graders (from 15% in 1992 to 35% in 1997), and nearly doubled among 12th graders (from 22% in 1992 to 39% in 1997). Among college students, however, the increase in marijuana use was much more gradual, presumably due to a generational replacement effect. Annual prevalence of use rose by about one third, from 27% in 1991 to 36% in 1998.
Monitoring The Future
Estimated 30-Day Prevalence of Use of Various Drugs for Grades 8, 10, and 12 Combined in the US, 1998-2016 - Entries are Percentages
"Crack cocaine use spread rapidly from the early to mid-1980s. Still, among 12th graders, the use of crack remained relatively low during this period (3.9% annual prevalence in 1987). Clearly, crack had quickly attained a reputation as a dangerous drug, and by the time of our first measurement of perceived risk in 1987, it was seen as the most dangerous of all drugs. Annual prevalence dropped sharply in the next few years, reaching 1.5% by 1991, where it remained through 1993.