Facility type
Hospital-based — 30.8 million
Freestanding — 22.6 million
Facility region
Northeast — 8.0 million
Midwest — 12.6 million
South — 24.0 million
West — 8.7 million
Facility metropolitan status
Metropolitan area — 45.7 million
Non-metropolitan area — 7.6 million
Source: National Center for Health Statistics’ 2006 National Survey of Ambulatory Surgery, Revised Public Use Data File.