| Many factors | Effective | Percentage |
| 1 | 42 | 8.0% |
| 2 | 143 | 27.3% |
| 3 | 133 | 25.4% |
| 4 | 108 | 20.6% |
| 5 | 81 | 15.5% |
| 6 | 16 | 3.0% |
| 7 | 1 | 0, 2% |
| Total | 524 | 100.0% |