Artful Dodger:

"Mental Illness disorders are prevalent in the United States. Approximately 26 percent of Americans 18 and older, that is one in four adults suffer from a diagnosed mental disorder. Mental disorders are the leading cause of disability in the U.S. for ages 15-44. It is estimated that many people suffer from more than one mental disorder at a time."

"If mental illness statistics compiled by the World Health Organization (WHO) is to be believed around 25 percent of the world population suffers from some or the other mental illness at some point of life. This and other such statistics on mental health problems reveal how severe this problem has become over the period of time."
As for the cost in the USA:

"The National Institute of Mental Health (NIMH) conservatively estimates the total costs associated with serious mental illness, those disorders that are severely debilitating and affect about 6 percent of the adult population, to be in excess of $300 billion per year. This estimate is based on 2002 data from the Substance Abuse and Mental Health Services Administration (SAMHSA), the Social Security Administration, and findings from the NIMH-funded National Comorbidity Survey – Replication (NCS-R). "

Obviously Europe is not alone in this. The world-wide estimated are at 25%, and the USA at 26%. That makes the USA no different from the average.

Our modern life is driven by overconsumption, overwork, war, economic crisis and political crisis. It comes as no surprise our societies are a mess.