This study compares prevalence and trends in marijuana use and marijuana use disorder from the National Epidemiologic Survey of Alcohol and Related Conditions with those from the National Survey on Drug Use and Health.  Over the past decade with the easing of state laws, the use of marijuana has increased by almost 20%.  However, based on DSM-IV psychiatric criteria the incidence of marijuana use disorder has decreased.  There are some weaknesses with this study as the questions were very subjective and does not take into the account other measures of abuse and other marijuana related disorders.

Source: JAMA Network | JAMA Psychiatry | Recent Trends in the Prevalence of Marijuana Use and Associated Disorders in the United States