"State and local law enforcement agencies made an estimated 1,336,500 arrests for drug possession or use in 2010. Females were 20% of these arrests. The median age in drug possession or use arrests was 26. Eleven percent of drug possession or use arrests in 2010 involved a juvenile, 18% involved persons age 40 or older, and 6% involved persons age 50 or older."
Snyder, Howard N., "Arrests in the United States, 1990-2010." Washington, DC: US Dept. of Justice Bureau of Justice Statistics. Oct. 2012. NCJ239423.