| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.9%
|
| 1949 | 1 |
0.9%
|
|
| 1962 | 1 |
0.9%
|
|
| 1973 | 1 |
0.9%
|
|
| 1974 | 1 |
0.9%
|
|
| 1976 | 1 |
0.9%
|
|
| 1977 | 1 |
0.9%
|
|
| 1980 | 1 |
0.9%
|
|
| 1982 | 2 |
1.8%
|
|
| 1983 | 1 |
0.9%
|
|
| 1984 | 3 |
2.6%
|
|
| 1986 | 1 |
0.9%
|
|
| 1989 | 1 |
0.9%
|
|
| 1990 | 5 |
4.4%
|
|
| 1991 | 1 |
0.9%
|
|
| 1992 | 1 |
0.9%
|
|
| 1994 | 2 |
1.8%
|
|
| 1995 | 1 |
0.9%
|
|
| 1996 | 2 |
1.8%
|
|
| 1998 | 3 |
2.6%
|
|
| 1999 | 2 |
1.8%
|
|
| 2000 | 7 |
6.1%
|
|
| 2001 | 3 |
2.6%
|
|
| 2002 | 1 |
0.9%
|
|
| 2003 | 2 |
1.8%
|
|
| 2004 | 3 |
2.6%
|
|
| 2005 | 2 |
1.8%
|
|
| 2006 | 3 |
2.6%
|
|
| 2007 | 2 |
1.8%
|
|
| 2008 | 2 |
1.8%
|
|
| 2009 | 1 |
0.9%
|
|
| 2010 | 7 |
6.1%
|
|
| 2011 | 2 |
1.8%
|
|
| 2012 | 3 |
2.6%
|
|
| 2013 | 4 |
3.5%
|
|
| 2014 | 2 |
1.8%
|
|
| 2015 | 8 |
7%
|
|
| 2016 | 4 |
3.5%
|
|
| 2017 | 1 |
0.9%
|
|
| 2018 | 7 |
6.1%
|
|
| 2019 | 3 |
2.6%
|
|
| 2020 | 2 |
1.8%
|
|
| 2021 | 2 |
1.8%
|
|
| 2022 | 6 |
5.3%
|
|
| 2023 | 4 |
3.5%
|