More than 63 million Americans now live in states where recreational marijuana use is legal — but that doesn’t mean more teens are smoking weed, according to new national data.

The 42nd annual Monitoring the Future study, commissioned by the National Institute on Drug Abuse, surveyed eighth-, 10th-, and 12th-grade students across the U.S. and found that self-reported use of drugs is down overall, and alcohol and tobacco use are at their lowest rates since the ’90s.

Marijuana use remained steady despite shifting attitudes about weed, particularly among young people.

“I don’t have an explanation,” Dr. Nora Volkow, director of the National Institute on Drug Abuse, told U.S. News. “This is somewhat surprising. We had predicted — based on the changes in legalization, culture in the U.S., as well as decreasing perceptions among teenagers that marijuana was harmful — that [accessibility and use] would go up. But it hasn’t gone up.”

Here’s what the survey found:

Marijuana use in the past month among eighth-graders dropped significantly in 2016 to 5.4 percent, from 6.5 percent in 2015.

Daily use among eighth-graders dropped in 2016 to 0.7 percent from 1.1 percent in 2015.

Among high school seniors, 22.5 percent report marijuana use in the past month and 6 percent report daily use. Both measures remained relatively stable from last year.

Rates of marijuana use in the past year among 10th-graders also remained stable compared to 2015 but are at their lowest levels in over two decades.

Marijuana and e-cigarettes are now more popular than regular cigarettes among teens.

38.3 percent of high school seniors in states with medical marijuana laws reported marijuana use in the past year, compared to 33.3 percent in non-medical marijuana states. Those findings align with previous survey data.

After recent additional ballot measures passed in the November election, a total of 28 states and Washington, D.C., now permit medical marijuana, and seven states allow recreational use by adults. A poll conducted by the state government found that teen marijuana use in Colorado declined after the recreational marijuana law took effect, despite concerns that legality would increase access.