Data were obtained from the 2002 (n=54,079), 2003 (n=55,230), 2004 (n=55,602), 2005 (n=55,905), 2006 (n=55,279), 2007 (n=55,435), 2008 (n=55,739), 2009 (n=55,772), 2010 (n=57,873), 2011 (n=58,397), and 2012 (n=55,268) National Survey on Drug Use and Health (NSDUH) public use data files, a combined total sample size of 614,579 U.S. individuals. The NSDUH, sponsored by the Substance Abuse and Mental Health Services Administration (SAMHSA), was designed to provide estimates of the prevalence of extra-medical use of legal and illegal drugs in U.S. community-based individuals aged 12 and older (SAMHSA, 2003, 2013). The survey employed a 50-state design with an independent multistage area probability sample for each of the 50 states and the District of Columbia. To increase the precision of estimates, African-Americans, Hispanics, and young people were oversampled. Response rates for completed surveys ranged from 73%–79%.
