| 3 Months | 1 Year | 3 Years | 5 Years | ||||||||||
| N | % | Std. Err. | N | % | Std. Err. | N | % | Std. Err. | N | % | Std. Err. | ||
| Total | All | 128 | 80.5% | 3.5% | 128 | 70.3% | 4.0% | 98 | 57.1% | 5.0% | 85 | 43.5% | 5.4% |
| Yearly Center Volume | 0-1 | 8 | 62.5% | 17.1% | 8 | 50.0% | 17.7% | 7 | 14.3% | 13.2% | 10 | 20.0% | 12.6% |
| 2-7 | 14 | 85.7% | 9.4% | 14 | 78.6% | 11.0% | 35 | 65.7% | 8.0% | 14 | 50.0% | 13.4% | |
| 8+ | 106 | 81.1% | 3.8% | 106 | 70.8% | 4.4% | 56 | 57.1% | 6.6% | 61 | 45.9% | 6.4% | |