| Value | Category | Cases | |
|---|---|---|---|
| 1971 | 1 |
0.3%
|
|
| 1980 | 2 |
0.5%
|
|
| 1981 | 1 |
0.3%
|
|
| 1986 | 1 |
0.3%
|
|
| 1987 | 1 |
0.3%
|
|
| 1989 | 2 |
0.5%
|
|
| 1991 | 1 |
0.3%
|
|
| 1994 | 1 |
0.3%
|
|
| 1995 | 2 |
0.5%
|
|
| 1996 | 4 |
1%
|
|
| 1997 | 2 |
0.5%
|
|
| 1998 | 3 |
0.8%
|
|
| 1999 | 4 |
1%
|
|
| 2000 | 11 |
2.8%
|
|
| 2001 | 11 |
2.8%
|
|
| 2002 | 33 |
8.5%
|
|
| 2003 | 30 |
7.8%
|
|
| 2004 | 66 |
17.1%
|
|
| 2005 | 97 |
25.1%
|
|
| 2006 | 65 |
16.8%
|
|
| 9999 | 9999. Don't Know | 49 |
12.7%
|
| Sysmiss | 612 |