| Value | Category | Cases | |
|---|---|---|---|
| -99 | Don't know | 26 |
70.3%
|
| 1975 | 1 |
2.7%
|
|
| 1996 | 1 |
2.7%
|
|
| 2000 | 1 |
2.7%
|
|
| 2001 | 4 |
10.8%
|
|
| 2005 | 2 |
5.4%
|
|
| 2007 | 1 |
2.7%
|
|
| 2009 | 1 |
2.7%
|
|
| Sysmiss | 149 |