CHICAGO (Reuters) – More than 45 million Americans, or 20 percent of U.S. adults, had some form of mental illness last year, and 11 million had a serious illness, U.S. government researchers reported on Thursday. Young adults aged 18 to 25 had the highest level of mental illness at 30 percent, while those aged 50 and older had the lowest, with 13.7 percent, said the report by the Substance Abuse and Mental Health Services Administration or SAMHSA. The rate, slightly higher than last year's 19.5 percent figure, reflected increasing depression, especially among the unemployed, SAMHSA, part of the National Institutes...