The most prevalent mental illness among children age 3 to 17 was attention-deficit hyperactivity disorder (ADHD) (6.8%). ADHD was twice as prevalent as behavioral or conduct disorders (3.5%), according to the report. Other prevalent disorders were anxiety (3.0%), depression (2.1%), and autism spectrum disorder (1.1%). The CDC also compiled data on past-year substance use disorders among children age 12 to 17 and found that 4.2% had an alcohol use disorder in the prior year and 4.7% had an illicit drug use disorder. Prevalence rates for some disorders varied by race and ethnicity. The lowest rate of ADHD, for example, was found among Hispanic children, behavioral or conduct disorders were highest among black non-Hispanic children, and autism spectrum disorder was most prevalent among white non-Hispanic children.