The GAO recently issued a report examining changes in the air ambulance industry in the last decade and the implications of these changes on the availability of air ambulances and patient services. The GAO found that while the number of patients transported by helicopter air ambulance increased by about 35% from 1999 through 2008, the number of dedicated air ambulance helicopters increased about 88 percent. There also was a shift away from a preponderance of hospital-affiliated air ambulances to a more even split between hospital-based and independent providers. The data was not conclusive, however, regarding whether these developments have provided useful flexibility or encouraged to medically unnecessary flights. The report also provides information on the relationship between federal and state oversight and regulation of the industry.