| Residency | Year | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | |
| Total | 71 | 102 | 132 | 140 | 127 | 139 | 148 | 182 | 168 | 146 |
| U.S. Resident | 66 | 98 | 130 | 138 | 125 | 137 | 148 | 177 | 163 | 145 |
| Nonresident Alien | 4 | 3 | 1 | 1 | 2 | 2 | - | 5 | 5 | 1 |
| Unknown | 1 | 1 | 1 | 1 | - | - | - | - | - | - |
| Total (%) | 100.0% | 100.0% | 100.0% | 100.0% | 100.0% | 100.0% | 100.0% | 100.0% | 100.0% | 100.0% |
| U.S. Resident | 93.0% | 96.1% | 98.5% | 98.6% | 98.4% | 98.6% | 100.0% | 97.3% | 97.0% | 99.3% |
| Nonresident Alien | 5.6% | 2.9% | 0.8% | 0.7% | 1.6% | 1.4% | - | 2.7% | 3.0% | 0.7% |
| Unknown | 1.4% | 1.0% | 0.8% | 0.7% | - | - | - | - | - | - |