| Residency | Year | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | |
| Total | 123 | 192 | 260 | 285 | 300 | 264 | 208 | 241 | 241 | 209 |
| U.S. Resident | 121 | 189 | 258 | 283 | 300 | 264 | 207 | 239 | 240 | 208 |
| Nonresident Alien | - | 2 | 1 | 1 | - | - | 1 | 2 | - | 1 |
| Unknown | 2 | 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 | 98.4% | 98.4% | 99.2% | 99.3% | 100.0% | 100.0% | 99.5% | 99.2% | 99.6% | 99.5% |
| Nonresident Alien | - | 1.0% | 0.4% | 0.4% | - | - | 0.5% | 0.8% | - | 0.5% |
| Unknown | 1.6% | 0.5% | 0.4% | 0.4% | - | - | - | - | 0.4% | - |