According to a recent report that analyzed a 2013 survey of office-based physicians:

• 95.3% were accepting new patients
• 68.9% were accepting new Medicaid patients
• 83.7% were accepting new Medicare patients
• 84.7% were accepting new privately insured patients

Source: "Acceptance of New Patients With Public and Private Insurance by Office-based Physicians: United States, 2013," NCHS Data Brief Number 195, National Center for Health Statistics/Centers for Disease Control and Prevention, March 2015, http://www.cdc.gov/nchs/data/databriefs/db195.htm