Table 2 Categories subclassified according to the number of operations performed

Number of operations performed	Category
	Cardiovascular surgery	General thoracic surgery
0	39	41
1–24	46	92
25–49	99	92
50–99	163	193
100–149	86	134
150–199	60	107
≧200	90	118
Total	583	777

Number of operations performed	Esophageal surgery
0	86
1–4	99
5–9	81
10–19	105
20–29	48
30–39	35
40–49	30
≧50	71
Total	555