Results of the 2013 Monitoring the Future survey show abuse of most types of prescription drugs among teens remained relatively stable in 2013. Over 40,000 students in grades 8, 10, and 12 participated in the 2013 survey, which tracks non-medical use of narcotics, amphetamines, and other types of prescription medications. Results were made available by the University of Michigan and the National Institute on Drug Abuse on December 18, 2013. In 2013, 21.5% of 12th graders said they had used prescription drugs without a prescription at least once in their lifetime, while 15% reported doing so within the last year. These numbers have remained at similar levels since 2008. Rates of abuse for specific prescription drugs saw mixed results. Compared to 2012, 12th graders reported a 2.2% decline in the non-medical use of Vicodin® and a 0.7% decline in the non-medical use of OxyContin®. Abuse of Adderall® among 12th graders saw a slight decrease to 7.4%, but remained 2% higher than the rate in 2009, when Monitoring the Future began tracking abuse of that drug. The survey’s authors noted that these numbers “would be consistent with the interpretation that older students may use Adderall to assist in studying.” The survey also showed that use of synthetic marijuana and “bath salts” declined significantly after Drug Enforcement Administration classified synthetic cannabinoids as a Schedule I substance, and that marijuana use among teens has continued to rise, with 6.5% of high school seniors now reporting daily or near-daily use.