| Value | Category | Cases | |
|---|---|---|---|
| 1999 | 1 |
25%
|
|
| 2003 | 1 |
25%
|
|
| 2011 | 1 |
25%
|
|
| 2013 | 1 |
25%
|
|
| 9998 | don't know | 0 |
0%
|
| Sysmiss | 35779 |