A statewide survey reports Colorado middle and high school students' use of marijuana has not increased since legalization.

The 2015 Healthy Kids Colorado Survey finds four of five high school students don’t use marijuana, even occasionally. That’s consistent with the numbers before marijuana was legalized in 2014, and about the same as the national rate.

The survey collected information from 17,000 randomly selected students from more than 150 middle and high schools.

Dr. Larry Wolk,  the state’s chief medical officer, suggests parental behavior is the most likely predictor of kids staying away from substances including marijuana. If a parent thinks it’s wrong to use marijuana, their child is four times less likely to use it, he says.