Marijuana use amongst Colorado teenagers has declined slightly since the state legalized recreational pot use among adults, according to a recent study.

A poll by the Colorado Department of Public Health and Environment showed that the percentage of high school students in Colorado who using pot was smaller than the national average, according to Scientific American.

“The survey shows marijuana use has not increased since legalization, with four of five high school students continuing to say they don’t use marijuana, even occasionally,” the department said in a statement.

According to the poll, 21.2% of Colorado teens used marijuana in 2015, which was down form the 22% in 2011, a year before recreational cannabis use for adults was approved statewide.

The national rate of pot use by teens is somewhat higher at 21.7%, according to Scientific American.

Some 17,000 students were surveyed by the department, which conducts the survey every two years in conjunction with the University of Colorado.

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