| Value | Category | Cases | |
|---|---|---|---|
| 1955 | 1 |
2.2%
|
|
| 1970 | 2 |
4.3%
|
|
| 1973 | 3 |
6.5%
|
|
| 1981 | 1 |
2.2%
|
|
| 1982 | 2 |
4.3%
|
|
| 1988 | 2 |
4.3%
|
|
| 1989 | 2 |
4.3%
|
|
| 1990 | 3 |
6.5%
|
|
| 1991 | 1 |
2.2%
|
|
| 1994 | 2 |
4.3%
|
|
| 1995 | 2 |
4.3%
|
|
| 1996 | 1 |
2.2%
|
|
| 1997 | 2 |
4.3%
|
|
| 1999 | 3 |
6.5%
|
|
| 2000 | 1 |
2.2%
|
|
| 2001 | 2 |
4.3%
|
|
| 2002 | 3 |
6.5%
|
|
| 2003 | 2 |
4.3%
|
|
| 2004 | 2 |
4.3%
|
|
| 2005 | 5 |
10.9%
|
|
| 2006 | 1 |
2.2%
|
|
| 9999 | 9999. Don't know | 3 |
6.5%
|
| Sysmiss | 953 |