As U.S. states begin to roll back prohibitions on marijuana, younger Americans are beginning to view the drug in a more favorable light.

A new survey out from the U.S. National Institutes of Health (NIH) this week is showing that teens’ attitudes toward marijuana are now softening. The report shows that more than 60% of U.S. 12th-graders do not view “regular marijuana use” as harmful. This is up from nearly 56% who viewed such use as harmful last year.

Teens’ attitudes toward marijuana have changed significantly in just the past decade. In 1993 around 70% of U.S. 12th-graders considered regular marijuana use harmful.

Teen use of marijuana has also increased significantly in the past two decades. The NIH found that 6.5% of U.S. 12th-graders smoke marijuana daily. That is up only slightly from the 6% who were found to be daily smokers one decade ago, but more than double the 2.4% of 12-graders who smoked marijuana daily in 1993.

The NIH also found that over one-third of U.S. 12th-graders had smoked marijuana within the past year.

“This is not just an issue of increased daily use,” said Dr. Nora Volkow, director of the National Institute on Drug Abuse. “It is important to remember that over the past two decades, levels of THC – the main psychoactive ingredient in marijuana – have gone up a great deal, from 3.75 percent in 1995 to an average of 15 percent in today’s marijuana cigarettes. Daily use today can have stronger effects on a developing teen brain than it did 10 or 20 years ago.”

The NIH’s “Monitoring the Future” survey measured drug use and attitudes toward drug use among 8th-, 10th-, and 12th-graders. In addition to the marijuana findings, the survey also found that the use of synthetic marijuana, inhalants, bath salts, salvia, MDMA, and cigarettes is down or very low among high schoolers. Cocaine and heroin use saw now significant change from last year’s survey, though both drugs are at historic lows for U.S. high schoolers.