| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 17 |
1.7%
|
| 1902 | 1 |
0.1%
|
|
| 1912 | 1 |
0.1%
|
|
| 1916 | 2 |
0.2%
|
|
| 1933 | 1 |
0.1%
|
|
| 1938 | 1 |
0.1%
|
|
| 1959 | 1 |
0.1%
|
|
| 1960 | 1 |
0.1%
|
|
| 1961 | 1 |
0.1%
|
|
| 1962 | 1 |
0.1%
|
|
| 1969 | 1 |
0.1%
|
|
| 1971 | 1 |
0.1%
|
|
| 1974 | 1 |
0.1%
|
|
| 1975 | 1 |
0.1%
|
|
| 1977 | 1 |
0.1%
|
|
| 1980 | 1 |
0.1%
|
|
| 1982 | 1 |
0.1%
|
|
| 1985 | 1 |
0.1%
|
|
| 1988 | 1 |
0.1%
|
|
| 1990 | 1 |
0.1%
|
|
| 1991 | 6 |
0.6%
|
|
| 1992 | 6 |
0.6%
|
|
| 1993 | 7 |
0.7%
|
|
| 1994 | 21 |
2.1%
|
|
| 1995 | 15 |
1.5%
|
|
| 1996 | 13 |
1.3%
|
|
| 1997 | 9 |
0.9%
|
|
| 1998 | 13 |
1.3%
|
|
| 1999 | 5 |
0.5%
|
|
| 2000 | 15 |
1.5%
|
|
| 2001 | 10 |
1%
|
|
| 2002 | 9 |
0.9%
|
|
| 2003 | 16 |
1.6%
|
|
| 2004 | 26 |
2.6%
|
|
| 2005 | 23 |
2.3%
|
|
| 2006 | 19 |
1.9%
|
|
| 2007 | 29 |
2.9%
|
|
| 2008 | 38 |
3.8%
|
|
| 2009 | 52 |
5.2%
|
|
| 2010 | 41 |
4.1%
|
|
| 2011 | 35 |
3.5%
|
|
| 2012 | 22 |
2.2%
|
|
| 2013 | 50 |
5%
|
|
| 2014 | 43 |
4.3%
|
|
| 2015 | 50 |
5%
|
|
| 2016 | 62 |
6.2%
|
|
| 2017 | 65 |
6.4%
|
|
| 2018 | 74 |
7.3%
|
|
| 2019 | 70 |
6.9%
|
|
| 2020 | 46 |
4.6%
|
|
| 2021 | 40 |
4%
|
|
| 2022 | 38 |
3.8%
|
|
| 2023 | 3 |
0.3%
|