More high school seniors smoke marijuana than cigarettes, according to the annual Monitoring the Future survey sponsored by the National Institute on Drug Abuse.

At 19.2 percent, the percentage of high school seniors who said they smoked cigarettes during the previous 30 days was the lowest since the survey began in 1975, and it was the first time the rate came in below 20 percent. In contrast, 8th and 10th graders showed small increases.

Marijuana use, meanwhile, increased at all three grade levels, continuing a recent trend. Among high school seniors, 21.4 percent reported smoking marijuana at least once in the last 30 days.

Still current rates of marijuana use are lower than they were in the ’70s and early ’80s, Time reports. Daily marijuana use peaked in 1978, when more than 10 percent of seniors reported daily marijuana smoking, versus 6.1 percent in this year’s survey.

The survey also found that all three grades reported more favorable attitudes toward the drug.

“Though this upward shift is not yet very large, its duration and pervasiveness leave no doubt in our minds that it is real,” said Lloyd Johnston, the principal investigator of the study.

Johnston blamed rising use among teens over the past three years on the public battles over medical marijuana. More than a dozen states and the District of Columbia have legalized medical marijuana, USA Today reports.

The National Institute on Drug Abuse plans to fund research into whether U.S. teens’ test scores and grades have fallen as marijuana use has risen.

According to the survey, which polled more than 46,000 teens, use of the drug ecstacy also is on the rise among teens, with significant increases among 8th- and 10th- graders.

Alcohol use, however, was down. For high school seniors, the percentage who said they drank within the previous 30 days–41.2 percent–was the lowest in the history of the survey.