| 3 Months | 1 Year | 3 Years | 5 Years | ||||||||||
| N | % | Std. Err. | N | % | Std. Err. | N | % | Std. Err. | N | % | Std. Err. | ||
| Total | All | 137 | 85.5% | 4.1% | 137 | 70.7% | 5.5% | 112 | 42.7% | 6.6% | 91 | 33.3% | 8.2% |
| Yearly Center Volume | 0-1 | 9 | 88.9% | 10.5% | 9 | 88.9% | 10.5% | 8 | 0.0% | 0.0% | 11 | 25.0% | 21.7% |
| 2-7 | 14 | 75.0% | 21.7% | 14 | 50.0% | 25.0% | 40 | 50.0% | 11.2% | 15 | 50.0% | 25.0% | |
| 8+ | 114 | 86.3% | 4.3% | 114 | 71.6% | 5.7% | 64 | 42.2% | 8.6% | 65 | 32.0% | 9.3% | |