Value | Category | Cases | |
---|---|---|---|
-9 | Don't know (spontaneous) | 0 |
0%
|
1936 | 1 |
0.3%
|
|
1947 | 1 |
0.3%
|
|
1954 | 1 |
0.3%
|
|
1957 | 1 |
0.3%
|
|
1958 | 1 |
0.3%
|
|
1963 | 1 |
0.3%
|
|
1964 | 3 |
0.8%
|
|
1965 | 2 |
0.6%
|
|
1966 | 1 |
0.3%
|
|
1967 | 1 |
0.3%
|
|
1969 | 1 |
0.3%
|
|
1972 | 1 |
0.3%
|
|
1975 | 1 |
0.3%
|
|
1977 | 1 |
0.3%
|
|
1979 | 1 |
0.3%
|
|
1984 | 1 |
0.3%
|
|
1987 | 2 |
0.6%
|
|
1990 | 1 |
0.3%
|
|
1991 | 6 |
1.7%
|
|
1992 | 6 |
1.7%
|
|
1993 | 8 |
2.3%
|
|
1994 | 9 |
2.5%
|
|
1995 | 14 |
4%
|
|
1996 | 16 |
4.5%
|
|
1997 | 9 |
2.5%
|
|
1998 | 13 |
3.7%
|
|
1999 | 10 |
2.8%
|
|
2000 | 15 |
4.2%
|
|
2001 | 7 |
2%
|
|
2002 | 10 |
2.8%
|
|
2003 | 12 |
3.4%
|
|
2004 | 11 |
3.1%
|
|
2005 | 10 |
2.8%
|
|
2006 | 14 |
4%
|
|
2007 | 21 |
5.9%
|
|
2008 | 12 |
3.4%
|
|
2009 | 14 |
4%
|
|
2010 | 9 |
2.5%
|
|
2011 | 10 |
2.8%
|
|
2012 | 8 |
2.3%
|
|
2013 | 12 |
3.4%
|
|
2014 | 14 |
4%
|
|
2015 | 13 |
3.7%
|
|
2016 | 8 |
2.3%
|
|
2017 | 9 |
2.5%
|
|
2018 | 7 |
2%
|
|
2019 | 13 |
3.7%
|
|
2020 | 5 |
1.4%
|
|
2021 | 3 |
0.8%
|
|
2022 | 4 |
1.1%
|