Marijuana is more popular than cigarettes among teens, a government survey says.

The Centers for Disease Control and Prevention reported Thursday that 23 percent of high school students said they recently smoked marijuana, while 18 percent said they had puffed cigarettes, The Associated Press said.

The number of teens who smoke has been on the decline for decades, the AP said.  Marijuana use has fluctuated, and recently rose.  At times, though, cigarette and marijuana use have been around the same level, but last year marked the first time marijuana use was clearly greater.

An earlier survey by the University of Michigan in 2010 said daily marijuana use had increased significantly among eight, 10th- and 12th-graders, with about one in 16 high school seniors using marijuana daily, USA Today said.

The 2010 survey's director told USA Today that young people "are more increasingly seeing marijuana as not dangerous."

More than a dozen states and the District of Columbia have legalized medical marijuana, so teens might tend to view the drug as beneficial, not risky, said Nora Volkow, director of the National Institute of Drug Abuse in 2010.

She said marijuana interferes with memory and learning, which is especially concerning for teens whose brains have not fully developed.