| Value | Category | Cases | |
|---|---|---|---|
| 1996 | 174 |
9.6%
|
|
| 1997 | 289 |
15.9%
|
|
| 1998 | 334 |
18.4%
|
|
| 1999 | 477 |
26.2%
|
|
| 2000 | 546 |
30%
|
|
| 9997 | inconsistent | 0 |
0%
|
| 9998 | dk | 0 |
0%
|
| Sysmiss | 2169 |