Teen marijuana use continues to shrink in popularity with teenagers, an odd phenomenon that has consistently proven true since Colorado legalized the drug in 2012.

Federal data released Tuesday shows that rates of teen marijuana use in Colorado and Washington-the first two states to legalize recreational marijuana-decreased more than the national average in 2014. Slightly fewer teens in the two states are reportedly using marijuana than in 2012, before legalization efforts passed.

The federal Substance Abuse and Mental Health Services Administration’s National Survey on Drug Use and Health is believed to be the first true national glimpse into whether teens are using more marijuana in the post-legalization era.

In Colorado, the rate of 12-17-year-olds who used marijuana in the past month dropped 1.4 percent, from 12.5 percent in 2013 to 11.13 percent in 2014. The survey in 2012, ahead of legalization, showed 11.16 percent of the age group recently used marijuana.

Similarly, past-year use for the age group dropped 2.4 percent, from 20.8 percent in 2013 to 18.4 percent in 2014. In 2012, the age group saw an 18.8 percent past-year usage rate.

Washington saw similar trends, with past-month teen use dropping 0.89 percent and past-year use dropping 1.9 percent over the same time.

Nationwide, the rate of past-month marijuana use among teens dropped 0.02 percent and the rate of past-year use dropped 0.42 percent.

“Decades of arresting and prosecuting countless adults failed to prevent teens from accessing and using marijuana. States like Colorado and Washington are taking a new approach and actually controlling the production and sale of marijuana,” said Mason Tvert, spokesman for the pro-legalization Marijuana Policy Project. “Their success has already inspired a handful of other states to adopt similar laws, and more are sure to follow.”

The survey results follow a report last week by Monitoring the Future-which has polled teens since 1975-that stated that for a third year in a row, marijuana use declined among teens.

Marijuana use declined among eighth- and 10th-graders, and was stagnant for 12th-graders, the survey found.

Colorado’s own data shows similar trends. The Colorado Department of Public Health and Environment in June released its biannual “Healthy Kids Colorado Survey,” which revealed that 4 out of 5 high school students continue to say they don’t use marijuana, even occasionally.

A similar report from 2014 showed that teen marijuana use in Colorado had slightly decreased since legalization.

About 21 percent of high school students in Colorado reported using marijuana within the past 30 days in 2015, down slightly from 22 percent in 2011, the year before voters backed legalization, according to the “Healthy Kids Colorado Survey.”

The 21 percent 30-day use in Colorado represents a drop of about 4 points since 2009, when medical marijuana stores proliferated across the state.

The surveys come as Colorado reached a milestone this month in terms of marijuana sales, surpassing $1 billion in legal, regulated cannabis sales in the first 10 months of 2016, a figure reported Dec. 12 by The Cannabist. The data included both recreational and medical sales, as well as related cannabis products.

“Survey after survey is finding little change in rates of teen marijuana use despite big changes in marijuana laws around the nation,” Tvert said. “Colorado and Washington are dispelling the myth that regulating marijuana for adult use will somehow cause an increase in use among adolescents.”