Check out this great article on National Institute of Mental Health (NIMH) website:
Mental disorders are common in the United States and internationally. An estimated 26.2 percent of Americans ages 18 and older — about one in four adults — suffer from a diagnosable mental disorder in a given year.1 When applied to the 2004 U.S. Census residential population estimate for ages 18 and older, this figure translates to 57.7 million people.2Even though mental disorders are widespread in the population, the main burden of illness is concentrated in a much smaller proportion — about 6 percent, or 1 in 17 — who suffer from a serious mental illness.
Read the full article here:
The Numbers Count: Mental Disorders in America