A national survey released Tuesday found teen marijuana usage rates decreased from 2013 to 2014 — a period marked by heightened national debate regarding marijuana policy and implementation of the nation’s first marijuana legalization laws. According to the annual Monitoring the Future Survey, sponsored by the National Institute on Drug Abuse (NIDA), rates of annual, monthly, and daily marijuana use dropped among 8th-, 10th-, and 12th-graders. More details are available in the researchers’ press…