Non-medical marijuana III: rite of passage or Russian roulette? / National Center on Addiction and Substance Abuse at Colombia University, June 2008
PDF - http://www.casacolumbia.org/articlefiles/380-Non-Medical_Marijuana_III.pdf
"Despite reported declines in teen marijuana use, in 2007 almost 11 million teens report having used marijuana. For those using the drug, four alarming trends are of grave concern for parents and teens."