| Value | Category | Cases | |
|---|---|---|---|
| -99 | DK | 0 |
0%
|
| -88 | Missing | 0 |
0%
|
| -77 | NA | 0 |
0%
|
| 1996 | 1 |
1.5%
|
|
| 1997 | 5 |
7.4%
|
|
| 1998 | 4 |
5.9%
|
|
| 1999 | 9 |
13.2%
|
|
| 2000 | 23 |
33.8%
|
|
| 2001 | 26 |
38.2%
|
|
| Sysmiss | 30 |