Fewer American teenagers are using illegal drugs or drinking alcohol, researchers reported Tuesday.

Rates are at a record low for eighth-graders, the team at the University of Michigan and the National Institutes of Health found, but there’s a troubling increase in marijuana use among older teens in some states.

A teen girl smokes a cigarette. Angela Rowlings / AP file

“Clearly our public health prevention efforts, as well as policy changes to reduce availability, are working to reduce teen drug use, especially among eighth graders,” said Dr. Nora Volkow, director of the National Institute on Drug Abuse, part of the NIH.

“However, when 6 percent of high school seniors are using marijuana daily, and new synthetics are continually flooding the illegal marketplace, we cannot be complacent. We also need to learn more about how teens interact with each other in this social media era, and how those behaviors affect substance use rates.”

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The survey of 45,473 students in eighth, 10th and 12th grade at 372 public and private schools found 48 percent of 12th graders admit to having used a drug illegally in the past year, compared to 49 percent in 2015 and 54 percent in 2000.

About a third of 10th graders have used any illicit drug and 17 percent of eighth graders have.

Just 5 percent of eighth graders — typically aged 13 and 14 — said they’d used marijuana in the past month, down a percentage point from last year. And less than 1 percent said they used it daily, although nearly 13 percent had tried it at least once.

But 6 percent of high school seniors, aged 17 and 18, say they use marijuana daily; 22 percent said they’d used it in the past month and 44 percent have tried it.

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That’s down from the peak in 1996, when 23 percent of eighth graders and nearly 50 percent of seniors had tried cannabis.

Kids are also rejecting synthetic marijuana, sold under names such as “K2” or “Spice.” Just 3.5 percent of the seniors surveyed said they’d tried it in the past year, compared to 5 percent last year and 11 percent in 2011.

The same goes for MDMA, also known as “Ecstasy” or “Molly.” Just 1 percent of eighth graders and 3 percent of 12th graders said they’d tried the drug in the past year. "That's still a lot of young people using these dangerous drugs without medical supervision, but the trending is in the right direction," said Lloyd Johnston of the University of Michigan, who led the annual survey.

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Opioids are a big worry in some parts of the country, but overall the survey found less than 5 percent of seniors had used an opioid without a prescription, down from 9.5 percent in 2004.

Far more kids try alcohol. About 23 percent of eighth graders and 61 percent of seniors said they’d had at least one drink. That’s way down from 70 percent of eighth graders and 88 percent of seniors in 1991, however.

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“The survey indicates that marijuana and e-cigarettes are more popular than regular tobacco cigarettes,” NIDA said.

About 12 percent of seniors said they’d vaped — used an e-cigarette — in the past month, compared to 10 percent who said they’d smoked a cigarette.

But in 1991, 10.7 percent of high school seniors said they smoked a half pack or more a day. “Twenty-five years later, that rate has dropped to only 1.8 percent, reflecting the success of widespread public health anti-smoking campaigns and policy changes,” NIDA said.