U.S. Teens Using More Marijuana, Less Alcohol

Some 6.1 percent of high-school seniors reported using marijuana this year on a "near daily" basis, up from 5.2 percent in 2009, according to the Monitoring the Future survey released by the National Institutes of Health. "Near-daily" use of marijuana means students reported using pot 20 times in the 30 days before the survey was taken.

Near daily marijuana use by 10th-graders climbed from 2.8 percent to 3.3 percent, and for eighth-grade students it edged up from 1.0 percent to 1.2 percent.

The rates for marijuana use at any time during the year were 34.8 percent for seniors, 27.5 percent in 10th grade and 13.7 percent among eighth graders.

On the other hand, binge drinking is on the decline. While 23.2 percent of high school seniors reported having five or more drinks in a row, that's down from 25.2 percent a year earlier. The binge rate for this age group peaked at 31.5 percent in 1998.

The study found that more high school seniors are smoking marijuana than tobacco. In 2010, 21.4 percent of seniors said they had toked pot within the past 30 days, while 19.2 percent said they had lit up cigarettes.