Value | Category | Cases | |
---|---|---|---|
-9 | Don't know (spontaneous) | 2 |
0.5%
|
1952 | 1 |
0.3%
|
|
1954 | 1 |
0.3%
|
|
1969 | 1 |
0.3%
|
|
1970 | 1 |
0.3%
|
|
1973 | 1 |
0.3%
|
|
1974 | 1 |
0.3%
|
|
1975 | 1 |
0.3%
|
|
1976 | 1 |
0.3%
|
|
1978 | 1 |
0.3%
|
|
1981 | 1 |
0.3%
|
|
1983 | 1 |
0.3%
|
|
1984 | 1 |
0.3%
|
|
1986 | 2 |
0.5%
|
|
1987 | 2 |
0.5%
|
|
1990 | 3 |
0.8%
|
|
1991 | 2 |
0.5%
|
|
1992 | 4 |
1.1%
|
|
1993 | 2 |
0.5%
|
|
1994 | 2 |
0.5%
|
|
1995 | 1 |
0.3%
|
|
1996 | 3 |
0.8%
|
|
1997 | 1 |
0.3%
|
|
1998 | 5 |
1.4%
|
|
1999 | 6 |
1.6%
|
|
2000 | 13 |
3.6%
|
|
2001 | 8 |
2.2%
|
|
2002 | 15 |
4.1%
|
|
2003 | 7 |
1.9%
|
|
2004 | 18 |
4.9%
|
|
2005 | 9 |
2.5%
|
|
2006 | 8 |
2.2%
|
|
2007 | 7 |
1.9%
|
|
2008 | 14 |
3.8%
|
|
2009 | 18 |
4.9%
|
|
2010 | 14 |
3.8%
|
|
2011 | 8 |
2.2%
|
|
2012 | 9 |
2.5%
|
|
2013 | 15 |
4.1%
|
|
2014 | 20 |
5.5%
|
|
2015 | 24 |
6.6%
|
|
2016 | 23 |
6.3%
|
|
2017 | 27 |
7.4%
|
|
2018 | 20 |
5.5%
|
|
2019 | 24 |
6.6%
|
|
2020 | 8 |
2.2%
|
|
2021 | 7 |
1.9%
|
|
2022 | 2 |
0.5%
|