I'm fairly certain a large chunk of the problem is demographic shift. healthcare is one of those industries most used by the elderly, and the proportion of the population in that demographic has skyrocketed
Also I would guess that there is more healthcare, more options, more procedures, more drugs. Length of stays in hospitals might have shortened due to less invasive procedures, but if more procedures are done and there is not increase in staffing, time is spread over larger number of patients.