Electronic Medical Record Use by Office-Based Physicians: United States, 2005

Here is the CDC link, the actual number using a full EHR is closer to 11.2%,SV

The latest data from the National Ambulatory Medical Care Survey (NAMCS) indicate that one-quarter of office-based physicians report using fully or partially electronic medical record systems (EMR) in 2005, a 31% increase from the 18.2 percent reported in the 2001 survey (1).

CDC