According to Daley and Moss (2002), the 1996 National Comorbidity Study of more than 8000 respondents found that lifetime rates for the general population are 26.6% for substance use disorder and 21.4% for mental disorder. Among those with mental health disorders, 51% have a coexisting substance use disorder. Among those with substance use disorders, 41-66% (depending on the drug of choice) have coexisting mental disorders.