| Value | Category | Cases | |
|---|---|---|---|
| -99 | Don't know | 20 |
26%
|
| 1998 | 1 |
1.3%
|
|
| 2009 | 1 |
1.3%
|
|
| 9888 | Continuing | 55 |
71.4%
|
| Sysmiss | 109 |