| Value | Category | Cases | |
|---|---|---|---|
| 1995 | 4 |
0.2%
|
|
| 1996 | 121 |
7.2%
|
|
| 1997 | 165 |
9.8%
|
|
| 1998 | 304 |
18%
|
|
| 1999 | 548 |
32.4%
|
|
| 2000 | 548 |
32.4%
|
|
| 9997 | inconsistent | 1 |
0.1%
|
| 9998 | dk | 0 |
0%
|
| Sysmiss | 5064 |