According to a recent study:

• 58% of hospitals exchanged data with providers outside their organization in 2012
• The proportion of hospitals that adopted at least a basic EHR (electronic health record) and participated in an HIO (Health Information Organization) grew more than fivefold from 2008 to 2012
• 84% of hospitals that adopted an EHR and participated in a regional HIO exchanged information with providers outside their organization
• Only about one-third of hospitals exchanged clinical care summaries or medication lists with outside providers

Source: "Data exchange growing through EHR adoption, new study finds," U.S. Department of Health & Human Services News Release, August 5, 2013, http://www.hhs.gov/news/press/2013pres/08/20130805a.html