Marijuana use rising in USOverall, 8.9 percent of the U.S. population or 22.6 million Americans aged 12 and older used illicit drugs in 2010, up from 8.7 percent in 2009 and 8 percent in 2008, according to the survey by the Substance Abuse and Mental Health Services Administration.
Marijuana use appeared to be fueling the increase, with some 17.4 million Americans -- or 6.9 percent of the population -- saying they used marijuana in 2010, up from 14.4 million or 5.8 percent of the population in 2007.
Gil Kerlikowske, director of the Office of National Drug Control Policy in the United States, said increases are especially prominent in states in which medical marijuana use is legal.
"Emerging research reveals potential links between state laws permitting access to smoked medical marijuana and higher rates of marijuana use," Kerlikowske said in a statement.
According to the survey, 21.5 percent of young adults aged 18 to 25 used illicit drugs in 2010, up from 19.6 percent in 2008 to 21.2 percent in 2009.
"This increase was also driven in large part by a rise in the rate of current marijuana use among this population," Kerlikowske said.
Use of methamphetamines, meanwhile, has decreased, the survey found.
The number of current meth users fell by about half between 2006 and 2010, with the number of people aged 12 and older who used meth dropping to 353,000 last year, down from 731,000 in 2006.
Cocaine use also fell, dropping to 1.5 million users in 2010, from 2.4 million in 2006, the survey found.
And among youths aged 12 to 17, drinking rates fell to 13.6 percent in 2010 from 14.7 percent in 2009; and smoking use fell to 10.7 percent in 2010, from 11.6 percent in 2009.