| 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 | 67.1% | 5.5% | 92 | 41.3% | 5.1% | 98 | 36.7% | 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% | 10 | 50.0% | 15.8% | 9 | 22.2% | 13.9% | |
| 8-13 | 14 | 85.7% | 9.4% | 14 | 78.6% | 11.0% | 17 | 41.2% | 11.9% | 11 | 54.5% | 15.0% | |
| 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% | 25 | 44.0% | 9.9% | 50 | 38.0% | 6.9% | |