Teens are better-behaved than ever when it comes to alcohol and drugs, but seem to have turned to vaping as their vice of choice, according to results from a nationally representative survey of adolescent drug use.

First, the good news. Teen smoking is still at the lowest point since the Monitoring the Future survey began 44 years ago. Only 3.6 percent of high schoolers are smoking daily, down from more than 22 percent a couple decades ago. Binge drinking is down, adolescents are using drugs like cocaine and MDMA at historically low levels, and, despite the ongoing opioid epidemic, less than 1 percent of high school seniors use heroin. Plus, the percentage of seniors using prescription opioids dropped to 3.4 percent from 4.2 percent a year earlier. When it comes to marijuana, the rates have held steady for the past few years despite increasing marijuana legalization. “We are not seeing decreases in marijuana, but we are not seeing increases,” says Nora Volkow, director of the National Institute on Drug Abuse (NIDA), at a press conference discussing the results. (NIDA and the University of Michigan administer the Monitoring the Future survey.)

For Volkow and others involved in the survey, the new concern is that these positive trends might be reversed by the rapid rise of vaping. From 2017 to this year, the number of seniors who reported vaping in the past 30 days jumped from 11 percent to 21 percent. That’s the largest single increase that the Monitoring the Future study has seen in its history, says Richard Miech, the survey’s principal investigator and a member of University of Michigan’s Institute for Social Research.

About 37.3 percent of seniors reported vaping at all in the last year, up from 27.8 percent of seniors last year. And whereas teens used to just vape flavors, now they’re getting more adventurous. “Anything that can be vaped, it doesn’t matter, it goes up,” says Meich. “Nicotine vaping went up, marijuana vaping went up, we asked kids if they vapored flavors and that went up, too.” For example, 13.1 percent of seniors reported vaping marijuana in the past year, up from 9.5 percent. “Something about this delivery device really appeals to kids,” Meich adds.

Overall, the results are consistent with a big shift in teen drug use. Previous research has suggested that teens are now trying marijuana before alcohol and tobacco, in part due to years of public health campaigns around the dangers of smoking and drinking. At the same time, e-cig manufacturers like Juul have been selling flavors that appeal to kids and marketing itself as a healthy alternative to smoking, even though its products are highly addictive. Even as users sue the manufacturer for getting them hooked on nicotine, vapes are increasingly the gateway drug of choice. To combat this, various organizations — including the US Food and Drug Administration — are kicking their anti-vaping campaigns into high gear. As tacky as these posters and ads might seem, they address a real issue. But we’ll have to wait until next year’s report to see if their message gets through.

Correction December 18th, 5:30PM EST: A previous version of this article said that the number of seniors vaping daily had increased from 11 percent to 21 percent.