Data are for the U.S.
Source: Summary Health Statistics Tables for U.S. Adults: National Health Interview Survey, 2015, Table A-4 [PDF – 232 KB]
Source: National Ambulatory Medical Care Survey: 2014 State and National Summary Tables, table 15 [PDF – 613 MB]
Source: National Hospital Ambulatory Medical Care Survey: 2014 Emergency Department Summary Tables, table 11 [PDF – 521 KB]