Availability of Marijuana Among Youth Measured by Monitoring The Future (MTF) Study
"Ever since the MTF study began in 1975, between 81% and 90% of 12th graders each year have said that they could get marijuana fairly easily or very easily if they wanted some. It has been considerably less accessible to younger adolescents. Still, in 2012, 37% of 8th graders, 69% of 10th graders, and 82% of 12th graders reported it as being fairly or very easy to get. It thus seems clear that marijuana has remained highly accessible to the older teens."
Johnston, L. D., O’Malley, P. M., Bachman, J. G., & Schulenberg, J. E. (2013). Monitoring the Future national results on adolescent drug use: Overview of key findings, 2012. Ann Arbor: Institute for Social Research, The University of Michigan, p. 12.