Value | Category | Cases | |
---|---|---|---|
-9 | Don't know (spontaneous) | 0 |
0%
|
1962 | 1 |
0.3%
|
|
1967 | 1 |
0.3%
|
|
1970 | 1 |
0.3%
|
|
1972 | 1 |
0.3%
|
|
1974 | 1 |
0.3%
|
|
1977 | 1 |
0.3%
|
|
1978 | 1 |
0.3%
|
|
1979 | 2 |
0.5%
|
|
1980 | 1 |
0.3%
|
|
1984 | 1 |
0.3%
|
|
1985 | 2 |
0.5%
|
|
1987 | 2 |
0.5%
|
|
1989 | 2 |
0.5%
|
|
1990 | 4 |
1.1%
|
|
1991 | 1 |
0.3%
|
|
1992 | 2 |
0.5%
|
|
1993 | 4 |
1.1%
|
|
1995 | 6 |
1.6%
|
|
1996 | 3 |
0.8%
|
|
1997 | 4 |
1.1%
|
|
1998 | 9 |
2.5%
|
|
1999 | 9 |
2.5%
|
|
2000 | 6 |
1.6%
|
|
2001 | 9 |
2.5%
|
|
2002 | 10 |
2.7%
|
|
2003 | 6 |
1.6%
|
|
2004 | 13 |
3.6%
|
|
2005 | 9 |
2.5%
|
|
2006 | 11 |
3%
|
|
2007 | 6 |
1.6%
|
|
2008 | 8 |
2.2%
|
|
2009 | 13 |
3.6%
|
|
2010 | 13 |
3.6%
|
|
2011 | 12 |
3.3%
|
|
2012 | 11 |
3%
|
|
2013 | 16 |
4.4%
|
|
2014 | 33 |
9.1%
|
|
2015 | 26 |
7.1%
|
|
2016 | 26 |
7.1%
|
|
2017 | 14 |
3.8%
|
|
2018 | 19 |
5.2%
|
|
2019 | 14 |
3.8%
|
|
2020 | 9 |
2.5%
|
|
2021 | 9 |
2.5%
|
|
2022 | 11 |
3%
|
|
2023 | 1 |
0.3%
|