Anonymous surveys given to about 40,000 Colorado students before and after legalization showed “no significant change” in marijuana use by children under 18 in the preceding 30 days.

Among high school students, use went from about 23 percent in 2005 to about 20 percent in 2014. Similarly, there was no significant change in use by kids younger than 13 in recent years.

But Colorado youth were much more likely than kids in other states to use marijuana, both before and after legalization, according to a national survey.

About 13 percent of Colorado minors 12-17 in 2014 had used marijuana in the last 30 days, the annual National Survey on Drug Use and Health said. That compared with about 7 percent of minors the same ages nationwide.