| Value | Category | Cases | |
|---|---|---|---|
| -8 | not collected | 0 |
0%
|
| 1992 | 1 |
0.1%
|
|
| 2001 | 156 |
17.8%
|
|
| 2002 | 252 |
28.7%
|
|
| 2003 | 359 |
40.9%
|
|
| 2004 | 110 |
12.5%
|
|
| Sysmiss | 27 |