| Value | Category | Cases | |
|---|---|---|---|
| -99 | Don't know | 36 |
54.5%
|
| 1977 | 1 |
1.5%
|
|
| 1983 | 1 |
1.5%
|
|
| 1994 | 1 |
1.5%
|
|
| 1995 | 1 |
1.5%
|
|
| 1996 | 1 |
1.5%
|
|
| 1998 | 1 |
1.5%
|
|
| 2000 | 3 |
4.5%
|
|
| 2002 | 3 |
4.5%
|
|
| 2003 | 3 |
4.5%
|
|
| 2004 | 4 |
6.1%
|
|
| 2005 | 4 |
6.1%
|
|
| 2006 | 1 |
1.5%
|
|
| 2007 | 2 |
3%
|
|
| 2008 | 1 |
1.5%
|
|
| 2009 | 3 |
4.5%
|
|
| Sysmiss | 120 |