| Value | Category | Cases | |
|---|---|---|---|
| 1991 | 1 |
3.7%
|
|
| 1992 | 2 |
7.4%
|
|
| 1994 | 2 |
7.4%
|
|
| 1997 | 3 |
11.1%
|
|
| 1998 | 5 |
18.5%
|
|
| 1999 | 3 |
11.1%
|
|
| 2000 | 2 |
7.4%
|
|
| 2001 | 2 |
7.4%
|
|
| 2002 | 2 |
7.4%
|
|
| 2003 | 1 |
3.7%
|
|
| 2006 | 1 |
3.7%
|
|
| 2011 | 1 |
3.7%
|
|
| 9998 | Don't know | 2 |
7.4%
|
| Sysmiss | 41985 |