| Frequency | SDCG (%) | NSG (%) | Total (%) | p-value |
|---|---|---|---|---|
| 1~5 | 12 (30.8) | 208 (72.7) | 220 (67.7) | <0.0001* |
| 6~10 | 14 (35.9) | 58 (20.3) | 72 (22.2) | |
| 11~15 | 5 (12.8) | 8 (2.8) | 13 (4.0) | |
| 16~20 | 2 (5.1) | 7 (2.4) | 9 (2.8) | |
| 21≧ | 6 (15.4) | 5 (1.7) | 11 (3.4) | |
| Total | 39 (12.0) | 286 (88.0) | 325 (100.0) |