| Residency | Year | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 1997 | 1998 | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | |
| Total | 144 | 171 | 124 | 193 | 260 | 286 | 303 | 265 | 209 | 242 |
| U.S. Resident | 140 | 168 | 122 | 190 | 258 | 284 | 303 | 265 | 208 | 240 |
| Nonresident Alien | - | - | - | 2 | 1 | 1 | - | - | 1 | 2 |
| Unknown | 4 | 3 | 2 | 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 | 97.2% | 98.2% | 98.4% | 98.4% | 99.2% | 99.3% | 100.0% | 100.0% | 99.5% | 99.2% |
| Nonresident Alien | - | - | - | 1.0% | 0.4% | 0.3% | - | - | 0.5% | 0.8% |
| Unknown | 2.8% | 1.8% | 1.6% | 0.5% | 0.4% | 0.3% | - | - | - | - |