[grovehaw]

In the UK the definitions have a fair amount of consensus and the loss of productivity is one of the motivations for a range of employers organisations to support this initiative.

The UK's Mental Health Foundation gives these figures:

   >  1. Mixed anxiety & depression is the most common mental disorder in Britain,
   >      with 7.8% of people meeting criteria for diagnosis.
   >  2. 4-10% of people in England will experience depression in their lifetime.
   >  3. Common mental health problems such as depression and anxiety are distributed 
   >       according to a gradient of economic disadvantage across society. The poorer 
   >       and more disadvantaged are disproprotionately[sic] affected by common mental health 
   >       problems and their adverse consequences.
   >  4. Mixed anxiety and depression has been estimated to cause one 
   >      fifth of days lost from work in Britain.
   >  5. One adult in six had a common mental disorder.

https://www.mentalhealth.org.uk/publications/fundamental-fac... [pdf]