The following were the 15 most frequently billed CPT codes by internists to Medicare in 2004 (from most to least frequent):
1. 99213
2. 99232
3. 99214
4. G0001
5. Q0136
6. 99233
7. 93010
8. 99231
9. 93000
10. 99312
11. 85025
12. 85610
13. J0880
14. 99212
15. 80061