Buried in the NEJM article Use of Electronic Health Records in U.S. Hospitals is the statistic that the proportion of hospitals that have full
implementation of EMR’s nearly doubles from 1.5 to 2.9% of all hospitals when the public domain VA VistA system is taken into account:

‘On the basis of these definitions, we found that 1.5% (95% confidence interval [CI], 1.1 to 2.0) of U.S. hospitals had a comprehensive electronic-records system implemented across all major clinical units and an additional 7.6% (95% CI, 6.8 to 8.1) had a basic system that included functionalities for physicians’ notes and nursing assessments in at least one clinical unit. When defined without the requirement for clinical notes, a basic electronic-records system was found in 10.9% of hospitals (95% CI, 9.7 to 12.0). If we include federal hospitals run by the Veterans Health Administration (VHA), the proportion of hospitals with comprehensive electronic-records systems increases to 2.9% (95% CI, 2.3 to 3.5), the proportion with basic systems that include clinicians’ notes increases to 7.9% (95% CI, 6.9 to 8.8), and the proportion with basic systems that do not include clinicians’ notes increases to 11.3% (95% CI, 10.2 to 12.5).’