Mental health???????????????????

I was looking at all of the mental health disorders on howstuffworks.com, and it was saying things like "anxiety disorder affects 40 million americans; 7.7 million suffer from PTSD; 15 million suffer from depression; 11 million have TTM; 20.9 million have mood disorders" and a ton of other ailments.
My sister and mother have a kind of mental illness and it has me thinking. Of the 130 million Americans, about 80million or so suffer from mental illness. Just wondering what you all think of this. Please back up your statements.
i do realize that people can have more than 1 condition simultainiously