Value | Category | Cases | |
---|---|---|---|
-9 | Don't know (spontaneous) | 3 |
0.7%
|
1925 | 1 |
0.2%
|
|
1928 | 1 |
0.2%
|
|
1933 | 1 |
0.2%
|
|
1945 | 1 |
0.2%
|
|
1947 | 1 |
0.2%
|
|
1949 | 2 |
0.5%
|
|
1950 | 1 |
0.2%
|
|
1952 | 1 |
0.2%
|
|
1953 | 1 |
0.2%
|
|
1955 | 1 |
0.2%
|
|
1956 | 1 |
0.2%
|
|
1960 | 1 |
0.2%
|
|
1962 | 1 |
0.2%
|
|
1964 | 1 |
0.2%
|
|
1965 | 1 |
0.2%
|
|
1967 | 1 |
0.2%
|
|
1968 | 1 |
0.2%
|
|
1970 | 3 |
0.7%
|
|
1971 | 1 |
0.2%
|
|
1972 | 1 |
0.2%
|
|
1974 | 2 |
0.5%
|
|
1975 | 1 |
0.2%
|
|
1976 | 1 |
0.2%
|
|
1977 | 2 |
0.5%
|
|
1984 | 2 |
0.5%
|
|
1985 | 2 |
0.5%
|
|
1986 | 1 |
0.2%
|
|
1987 | 1 |
0.2%
|
|
1988 | 1 |
0.2%
|
|
1989 | 6 |
1.5%
|
|
1990 | 3 |
0.7%
|
|
1991 | 5 |
1.2%
|
|
1992 | 5 |
1.2%
|
|
1993 | 3 |
0.7%
|
|
1994 | 5 |
1.2%
|
|
1995 | 2 |
0.5%
|
|
1996 | 4 |
1%
|
|
1997 | 7 |
1.7%
|
|
1998 | 15 |
3.7%
|
|
1999 | 3 |
0.7%
|
|
2000 | 22 |
5.5%
|
|
2001 | 4 |
1%
|
|
2002 | 14 |
3.5%
|
|
2003 | 9 |
2.2%
|
|
2004 | 9 |
2.2%
|
|
2005 | 8 |
2%
|
|
2006 | 7 |
1.7%
|
|
2007 | 12 |
3%
|
|
2008 | 9 |
2.2%
|
|
2009 | 10 |
2.5%
|
|
2010 | 18 |
4.5%
|
|
2011 | 20 |
5%
|
|
2012 | 14 |
3.5%
|
|
2013 | 14 |
3.5%
|
|
2014 | 13 |
3.2%
|
|
2015 | 14 |
3.5%
|
|
2016 | 21 |
5.2%
|
|
2017 | 23 |
5.7%
|
|
2018 | 18 |
4.5%
|
|
2019 | 25 |
6.2%
|
|
2020 | 16 |
4%
|
|
2021 | 5 |
1.2%
|