| Residency | Year | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 1997 | 1998 | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | |
| Total | 118 | 148 | 237 | 344 | 464 | 487 | 534 | 420 | 330 | 289 |
| U.S. Resident | 115 | 147 | 235 | 343 | 462 | 486 | 534 | 420 | 330 | 289 |
| Nonresident Alien | - | - | 1 | - | - | - | - | - | - | - |
| Unknown | 3 | 1 | 1 | 1 | 2 | 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 | 97.5% | 99.3% | 99.2% | 99.7% | 99.6% | 99.8% | 100.0% | 100.0% | 100.0% | 100.0% |
| Nonresident Alien | - | - | 0.4% | - | - | - | - | - | - | - |
| Unknown | 2.5% | 0.7% | 0.4% | 0.3% | 0.4% | 0.2% | - | - | - | - |