large part of consumer expenditures, and consumer expenditures constitute roughly 70% of the US GDP. 

US people are poorer now, albeit with the government's relentless propaganda that the US economic condition is becoming better.  When people are poorer, they cut everything that are discretionary.  Obviously, the extremely expensive medical costs come up high on their lists.  These years US people see doctors less, take expensive medical tests less, buy expensive drugs less and switch to generics.  That's why so many clinics are in trouble, closing one by one, and many doctors fold their own businesses to seek jobs in hospitals or public services.  The wind has changed.