| Value | Category | Cases | |
|---|---|---|---|
| 0 | 68 |
11.1%
|
|
| 1 | Before 1990 | 149 |
24.4%
|
| 2 | From 1990-95 | 110 |
18%
|
| 3 | since 1995 | 202 |
33.1%
|
| 4 | 2001-2002 | 58 |
9.5%
|
| 9 | Don't know | 23 |
3.8%
|
| Sysmiss | 2323 |