Results from the annual National Survey on Drug Use and Health, released today, have found marijuana use is on the rise, while methamphetamine use is on the decline.

USA Today reports the survey, sponsored by the Substance Abuse and Mental Health Services Administration (SAMHSA), found 8.7 percent of Americans say they regularly use illegal drugs recreationally, the same rate as 2009, but above the 2008 rate of 8 percent. The most popular drug is marijuana, with 17.4 million regular users. In 2007, 14.4 million Americans said they used marijuana.

An estimated 6.9 percent of those surveyed said they use marijuana regularly, compared with 5.8 percent in 2007. Among 12- to 17-year-olds, 7.4 percent said they had used marijuana in the previous month in 2010, about the same percentage as 2009. Among 18- to 25-year-olds, 18.5 percent said they used marijuana in 2010, up from 16.5 percent in 2008.

Gil Kerlikowske, Director of the Office of National Drug Control Policy, attributed the increase in marijuana use to the growing number of states that approved marijuana for medical use. In a news release issued by SAMHSA, Kerlikowske said, “Emerging research reveals potential links between state laws permitting access to smoked medical marijuana and higher rates of marijuana use.” In May, Delaware became the 16th state to legalize medical marijuana.

The survey found the number of people who said they used methamphetamines in the past month dropped from 731,000 in 2006 to 353,000 in 2010. The percentage of people who used prescription drugs for non-medical reasons stayed at 2.7 percent between 2009 and 2010.