"• Figure 5-4a and Table 5-5d provide trends in daily marijuana use, defined as using marijuana on 20 or more occasions in the prior 30 days. Among 12th grade students, the 2019 level of 6.4% is the highest level recorded by the survey since 2013. About one in every 16 twelfth grade students in 2019 was a daily or near-daily marijuana user. Daily marijuana use significantly increased in 8th and 10th grade in 2019, to 1.3% and 4.8%, respectively.

"In context, the percentage of youth using marijuana on a daily or near-daily basis today is substantially lower than its peak in the late 1970s, when it reached a high of 10.7% among 12th grade students, or about one in every nine students. As discussed in Chapter 8, we think much of the decline from this peak is attributable to a very substantial increase in teens’ concerns about possible adverse effects from regular use and to a growing perception that peers disapproved of marijuana use, particularly regular use. In recent years teens have reported less concern about marijuana’s potential adverse effects and less disapproval of it (reported in Chapter 8), and daily use has risen considerably since the early 1990s.

"• Table 5-4 presents trend data on lifetime daily marijuana use for a month or more (this question is asked only of 12th grade students and on only one form). Prevalence in 2019 (15%) is between the high of 21% (set in 1982, when first measured by the survey) and the low of 8% (set in 1992, just before the 1990s drug relapse). Before 2011, prevalence hovered at around 16% since 1996, then rose in 2011 and 2012 along with current daily use, before declining some and then remaining stable in recent years. In a pattern seen with many other drugs, prevalence increased considerably during the 1990s relapse (from 1992 to 1997) having decreased considerably prior to the relapse.

"• Medical marijuana prescriptions for adolescents have been surveyed since 2017 and are rare. In all grades and in all years, fewer than 1.5% of adolescents reported that they had ever used marijuana because a doctor told them to do so.

"• Annual prevalence of synthetic marijuana has decreased dramatically since it was first tracked by Monitoring the Future in 2011 for 12th graders and 2012 for 8th and 10th graders (Table 5-5b and Figure 5-4b). For 12th graders, annual prevalence declined from 11.4% in 2011 to 3.3% in 2019, a drop of more than two-thirds. For 10th graders, annual prevalence declined from 8.8% in 2012 to 2.6% in 2019. For 8th graders the decline was from 4.4% in 2012 to 2.12 in 2019.

"The current 2.7% level in 8th grade reflects a significant 1.1 percentage point increase in 2019, which is concerning. It may be that 8th graders are confusing synthetic marijuana with marijuana vaping, which increased significantly in 2019 (discussed below). This could explain the unusual finding of a slightly higher prevalence among 8th as compared to 10th grade students."