The National Comorbidity Survey Replication (NCS-R, 2001-2002) estimates that 32.6 to 35.1 million adults (16.2%) experience major depressive disorder at some point in their lives. Major depressive disorder is a serious disorder that is different from normal temporary feelings of sadness. An estimated 13.1 to 14.2 million adults (6.6%) experience major depressive disorder within a given year.
Adults with major depressive disorder in the past twelve months reported an average of 35.2 days in the past year that they were totally unable to work or carry out normal activities due to depression. Those with very severe role impairment missed an average of 96.5 days of work or normal activities.
Source: Kessler, Berglund, Demler, et al. (2003)
Surveys: National Comorbidity Survey Replication (NCS-R), 2001-2002