Value | Category | Cases | |
---|---|---|---|
-9 | Don't know (spontaneous) | 0 |
0%
|
1953 | 1 |
0.2%
|
|
1954 | 1 |
0.2%
|
|
1960 | 3 |
0.5%
|
|
1962 | 1 |
0.2%
|
|
1964 | 1 |
0.2%
|
|
1965 | 1 |
0.2%
|
|
1969 | 1 |
0.2%
|
|
1970 | 2 |
0.3%
|
|
1972 | 2 |
0.3%
|
|
1973 | 1 |
0.2%
|
|
1974 | 2 |
0.3%
|
|
1975 | 2 |
0.3%
|
|
1976 | 3 |
0.5%
|
|
1977 | 1 |
0.2%
|
|
1978 | 3 |
0.5%
|
|
1979 | 2 |
0.3%
|
|
1980 | 2 |
0.3%
|
|
1981 | 1 |
0.2%
|
|
1982 | 3 |
0.5%
|
|
1983 | 4 |
0.7%
|
|
1984 | 4 |
0.7%
|
|
1985 | 2 |
0.3%
|
|
1986 | 4 |
0.7%
|
|
1988 | 1 |
0.2%
|
|
1989 | 6 |
1%
|
|
1990 | 3 |
0.5%
|
|
1991 | 5 |
0.8%
|
|
1992 | 5 |
0.8%
|
|
1993 | 6 |
1%
|
|
1994 | 8 |
1.4%
|
|
1995 | 8 |
1.4%
|
|
1996 | 10 |
1.7%
|
|
1997 | 8 |
1.4%
|
|
1998 | 7 |
1.2%
|
|
1999 | 13 |
2.2%
|
|
2000 | 11 |
1.9%
|
|
2001 | 10 |
1.7%
|
|
2002 | 12 |
2%
|
|
2003 | 17 |
2.9%
|
|
2004 | 19 |
3.2%
|
|
2005 | 13 |
2.2%
|
|
2006 | 15 |
2.5%
|
|
2007 | 13 |
2.2%
|
|
2008 | 20 |
3.4%
|
|
2009 | 26 |
4.4%
|
|
2010 | 25 |
4.2%
|
|
2011 | 21 |
3.5%
|
|
2012 | 23 |
3.9%
|
|
2013 | 32 |
5.4%
|
|
2014 | 20 |
3.4%
|
|
2015 | 25 |
4.2%
|
|
2016 | 26 |
4.4%
|
|
2017 | 20 |
3.4%
|
|
2018 | 28 |
4.7%
|
|
2019 | 20 |
3.4%
|
|
2020 | 17 |
2.9%
|
|
2021 | 19 |
3.2%
|
|
2022 | 32 |
5.4%
|
|
2023 | 1 |
0.2%
|