| Previous IN Tx | Year | |||||||||
| 1993 | 1994 | 1995 | 1996 | 1997 | 1998 | 1999 | 2000 | 2001 | 2002 | |
| Total | 41 | 45 | 65 | 82 | 102 | 134 | 155 | 192 | 238 | 299 |
| No | 39 | 44 | 63 | 79 | 97 | 126 | 144 | 177 | 227 | 283 |
| Yes | 2 | 1 | 2 | 3 | 5 | 8 | 11 | 15 | 11 | 16 |
| Total (%) | 100.0% | 100.0% | 100.0% | 100.0% | 100.0% | 100.0% | 100.0% | 100.0% | 100.0% | 100.0% |
| No | 95.1% | 97.8% | 96.9% | 96.3% | 95.1% | 94.0% | 92.9% | 92.2% | 95.4% | 94.6% |
| Yes | 4.9% | 2.2% | 3.1% | 3.7% | 4.9% | 6.0% | 7.1% | 7.8% | 4.6% | 5.4% |