| 3 Months | 1 Year | 3 Years | 5 Years | ||||||||||
| N | % | Std. Err. | N | % | Std. Err. | N | % | Std. Err. | N | % | Std. Err. | ||
| Total | All | 73 | 78.1% | 4.8% | 73 | 67.0% | 5.5% | 97 | 39.9% | 5.0% | 99 | 37.8% | 4.9% |
| Yearly Center Volume | 0-4 | 9 | 77.8% | 13.9% | 9 | 66.7% | 15.7% | 9 | 33.3% | 15.7% | 12 | 41.7% | 14.2% |
| 5-7 | 5 | 60.0% | 21.9% | 5 | 20.0% | 17.9% | 12 | 48.6% | 14.8% | 9 | 22.2% | 13.9% | |
| 8-13 | 14 | 85.7% | 9.4% | 14 | 78.6% | 11.0% | 19 | 36.1% | 11.2% | 12 | 58.3% | 14.2% | |
| 14-22 | 13 | 61.5% | 13.5% | 13 | 53.8% | 13.8% | 31 | 38.7% | 8.7% | 16 | 25.0% | 10.8% | |
| 23+ | 32 | 84.4% | 6.4% | 32 | 75.0% | 7.7% | 26 | 42.3% | 9.7% | 50 | 38.7% | 7.0% | |