The number of Americans using illegal drugs has continued to rise, reaching 22.6 million, or 8.9 percent of the population, in 2010, a new government survey shows.

The increase has largely been driven by more marijuana use, according to the U.S. Substance Abuse and Mental Health Services Administration. In fact, in 2010 some 17.4 million Americans were using marijuana, compared with 14.4 million in 2007, the researchers found. This is an increase in the rate of marijuana use from 5.8 percent in 2007 to 6.9 percent in 2010.

"I don't know why there is an increase in marijuana, but that almost explains the increase in drug use," said Peter J. Delany, director of SAMHSA's Office of Applied Studies. "That's the driving trend."

In addition, young adults appear to be the group showing the greatest increase in drug use. "The group that seems to be standing out among everybody is the 18- to 25-year-olds," Delany said. "These are the people who are going to college, starting in the workforce and starting families."

Illicit drug use among this group has gone from 19.6 percent in 2008 to 21.5 percent in 2010, a significant increase, Delany said.

The illicit use of prescription painkillers has also been increasing, with most (55 percent) getting these drugs from a friend or relative. Only 4.4 percent of those using these drugs got them from a drug dealer, and less than 1 percent purchased them over the Internet, the report found.

Source: USA Today
http://yourlife.usatoday.com/health/story/2011-09-10/Study-More-US-adults-using-illegal-drugs/50340004/1