In 2016, rates of marijuana use among the nation’s 12- to 17-year-olds dropped to their lowest level in more than two decades, according to federal survey data released this week.

Last year, 6.5 percent of adolescents used marijuana on a monthly basis, according to the latest National Survey on Drug Use and Health. That represents a statistically significant drop from 2014, when the nation’s first recreational marijuana shops opened in Washington state and Colorado.

The last time monthly teen marijuana use was this low was 1994, according to the survey.

Public health experts tend to worry more about adolescent than adult drug use because adolescent brains are still developing. Teen drug use is linked to a host of health problems later in life, including addiction, criminal behavior and cognitive deficits.

The marijuana trend defies the warnings of those who oppose its legalization, who have long predicted that loosening restrictions on marijuana would “send the wrong message” to teens and increase teen drug use.

The federal data show that adult marijuana use, on the other hand, is rising. Last year 20.8 percent of Americans between the ages of 18 and 25 used marijuana at least monthly, the highest number since 1985. Among adults ages 26 to 34, 14.5 percent used marijuana monthly in 2016, also the most since 1985. [Read more at The Washington Post]