These 2010 prevalence estimates are similar to estimates from previous years and give no indication of dramatic increases or decreases. NSDUH is an annual survey of approximately 67,500 persons in the civilian, noninstitutionalized population age 12 and older conducted by the Substance Abuse and Mental Health Services Administration (SAMHSA). The survey covers residents of households and persons in noninstitutional group quarters (such as shelters, rooming and boarding houses, college dormitories, and halfway houses). Excluded are persons with no fixed household address, active-duty military personnel, and residents of institutional group quarters (such as correctional facilities, nursing homes, and long-term hospitals). Because of its statistical power, it is the nation's premier source of statistical information on the scope and nature of many behavioral health issues. The NSDUH defines mental illness among adults as having had a diagnosable mental, behavioral, or emotional disorder (excluding developmental and substance use disorders) in the past year on the basis of DSM-IV criteria. A serious mental illness is defined as one that results in functional impairment that substantially interferes with or limits one or more major life activities.