According to a recent analysis of data from the e-prescription network Surescripts:

• By April 2014, 70% of physicians were e-prescribing using an electronic health record (EHR)
• Only 7% of physicians were e-prescribing using an EHR when the Medicare Improvements for Patients and Providers Act (MIPPA) was passed in December of 2008
• 24% of physicians were e-prescribing using an EHR when the Medicare and Medicaid EHR Incentive Programs began in 2011

Source: "E-Prescribing Trends in the United States ," The Office of the National Coordinator for Health Information Technology (ONC), ONC Data Brief no. 18, July 2014, http://healthit.gov/sites/default/files/oncdatabriefe-prescribingincreases2014.pdf