An estimated 43.7 million U.S. adults (18.4%) reported experiencing mental illness in the past year when surveyed between 2012 and 2014, according to a new report by the Substance Abuse and Mental Health Services Administration. State estimates ranged from 15.8% in New Jersey to 22.7% in Oregon, with increases reported in four states: California, Maine, North Carolina and Rhode Island. The findings are based on data from the National Survey on Drug Use and Health.