Per John Hopkins Medical:
An estimated 26% of Americans ages 18 and older -- about 1 in 4 adults -- suffers from a diagnosable mental disorder in a given year. Many people suffer from more than one mental disorder at a given time. In particular, depressive illnesses tend to co-occur with substance use and anxiety disorders.
Per US News:
The United States ranks 29th in the world in prevalence of depressive disorders, with a rate of about 5%, or about 15 million Americans, estimated to have some form of depression. It is the largest country on the top 30 list of countries with the highest depression rates.