When U.S. health officials talk about the youth vaping epidemic, they’re mostly talking about the millions of teenagers who use products like Juul e-cigarettes to vape nicotine. But new federal data show that marijuana vaping is also on the rise among the nation’s teenagers.

Almost 21% of U.S. high school seniors said they had vaped marijuana in 2019, while 14% had done so in the past month and 3.5% said they did so every day, according to the annual Monitoring the Future Survey conducted by the University of Michigan on behalf of the National Institute on Drug Abuse. The survey’s results around marijuana vaping were published in JAMA, and, like the rest of the data, were based on information from 42,500 eighth, 10th and 12th graders in public and private schools nationwide.

The jump in past-month marijuana vaping—from 7.5% in 2018 to 14% this year among 12th graders—was the second-largest one-year increase ever recorded by the survey, behind only the historic increase in youth nicotine vaping from 2017 to 2018. But the 36% of seniors who said they had used marijuana in some form in 2019 was roughly the same as last year, suggesting that vaping is replacing smoking for some teens.

That’s concerning given the outbreak of lung disease that appears to be related to vaping products containing THC, particularly bootleg products purchased on the street. According to the U.S. Centers for Disease Control and Prevention’s (CDC) latest update, more than 2,400 people have been sickened and 52 have died during the outbreak. People as young as 13 have been diagnosed with these lung injuries, and patients as young as 17 have died.

Despite the rising popularity of marijuana vaping, it is still less widespread than nicotine vaping, according to the survey. A quarter of high school seniors said they had vaped nicotine in the past month, and almost 12% said they did so daily. About 8% said they vaped because they were “hooked.” U.S. Department of Health and Human Services data from September said 27.5% of high school students across grades had vaped in the past month.

At the same time, however, Monitoring the Future shows that cigarette smoking continues to plummet. Just 2.4% of 12th graders said they smoked every day in 2019, compared to 3.6% last year and about 11% of high schoolers a decade ago, according to federal data. Whether that’s because kids are switching from cigarettes to e-cigarettes remains unclear.

Underage drinking also continues to decline. Fifty-two percent of high school seniors said they drank alcohol in 2019, down a percentage point from last year and way below the 66% who said they had a decade ago. Binge-drinking—defined as consuming five or more drinks in a row—is also getting less common. Just 14% of seniors said they had done so in 2019, compared to a quarter in 2009.

Prescription drug abuse, as well as use of harder drugs such as cocaine and ecstasy, remains infrequent, according to the survey.

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Write to Jamie Ducharme at jamie.ducharme@time.com.