"• Marijuana is by far the most widely used illicit drug. Nearly half of all 12th graders (45%), nearly one third of 10th graders (31%), and over one in seven 8th graders (14%) reported some marijuana use in their lifetime. Among 12th graders, 37% reported some use in the past year, and 23% reported some use in the past month. Among 10th graders, the corresponding percentages were 26% and 16%, respectively, and among 8th grade students, 10% and 5.5%.

"• Current daily marijuana use or near daily use (defined as use on 20 or more occasions in the past 30 days) is also noteworthy. About one in 17 twelfth graders (5.9%) used marijuana daily in the month prior to the survey, as did one in 34 tenth graders (2.9%) and one in 125 eighth graders (0.8%).

"• Using the questions on duration of daily use, we have found that, since 1982, the lifetime prevalence of daily marijuana use for a month or more has been far higher than the prevalence of current daily marijuana use. For example, among 12th graders in 2017, 14% reported using marijuana daily for at least a month at some point in their lives, which is more than twice as high as the 5.9% reporting current daily use. In past years the ratio was higher; for example, in 1988 the lifetime prevalence was more than four times as high as current prevalence (13% compared to 3%).

"• Use of synthetic marijuana has declined recently and in 2017 is fairly low, with annual prevalence levels at 2.0%, 2.7%, and 3.7% in 8th, 10th, and 12th grade, respectively.

"• Marijuana vaping has emerged in recent years as a new way to use marijuana. In 2017 the portion of adolescents who had ever tried it was 12%, 10%, and 4% in 12th, 10th, and 8th grade, respectively. The much higher levels of overall lifetime marijuana use indicate that traditional ways to use marijuana, such as smoking it, currently remain more common than vaping."