| Value | Category | Cases | |
|---|---|---|---|
| 0 | 73 |
15.7%
|
|
| 1 | Before 1990 | 110 |
23.6%
|
| 2 | From 1990-95 | 81 |
17.4%
|
| 3 | since 1995 | 151 |
32.4%
|
| 4 | 2001-2002 | 35 |
7.5%
|
| 9 | Don't know | 16 |
3.4%
|
| Sysmiss | 2467 |