Table 2.

Characteristics of 12,223 Physicians.^*

Variable	No. (%)
Sex
Female	3,687 (30)
Male	8,536 (70)
Board certification
Yes	11,250 (92)
No	973 (8)
Medical school
Domestic	10,205 (83)
International	2,018 (17)
Years in practice†
<10	1,951 (16)
10–19	3,784 (31)
20–29	3,465 (28)
30–39	2,099 (17)
40–49	777 (6)
≥50 yr	147 (1)
Degree‡
D.O.	267/12,210 (2)
M.D.	11,943/12,210 (98)

^*Data are provided for the 12,223 physicians who could be linked to data from the Board of Registration — or 95.6% of the 12,789 physicians in the study population.

^†The number of years in practice was defined as the time from the year of medical school graduation to January 1, 2005 (the midpoint of the study period).

^‡Data on type of medical degree were missing for 13 physicians.