| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.4%
|
| 1861 | 1 |
0.4%
|
|
| 1873 | 1 |
0.4%
|
|
| 1878 | 1 |
0.4%
|
|
| 1885 | 1 |
0.4%
|
|
| 1924 | 1 |
0.4%
|
|
| 1928 | 1 |
0.4%
|
|
| 1938 | 1 |
0.4%
|
|
| 1946 | 1 |
0.4%
|
|
| 1949 | 2 |
0.7%
|
|
| 1969 | 1 |
0.4%
|
|
| 1977 | 1 |
0.4%
|
|
| 1983 | 1 |
0.4%
|
|
| 1986 | 1 |
0.4%
|
|
| 1990 | 9 |
3.4%
|
|
| 1991 | 23 |
8.6%
|
|
| 1992 | 16 |
6%
|
|
| 1993 | 16 |
6%
|
|
| 1994 | 15 |
5.6%
|
|
| 1995 | 13 |
4.9%
|
|
| 1996 | 8 |
3%
|
|
| 1997 | 11 |
4.1%
|
|
| 1998 | 6 |
2.2%
|
|
| 1999 | 5 |
1.9%
|
|
| 2000 | 7 |
2.6%
|
|
| 2001 | 7 |
2.6%
|
|
| 2002 | 1 |
0.4%
|
|
| 2003 | 6 |
2.2%
|
|
| 2004 | 8 |
3%
|
|
| 2005 | 7 |
2.6%
|
|
| 2006 | 7 |
2.6%
|
|
| 2007 | 9 |
3.4%
|
|
| 2008 | 8 |
3%
|
|
| 2009 | 8 |
3%
|
|
| 2010 | 7 |
2.6%
|
|
| 2011 | 4 |
1.5%
|
|
| 2012 | 6 |
2.2%
|
|
| 2013 | 5 |
1.9%
|
|
| 2014 | 6 |
2.2%
|
|
| 2015 | 3 |
1.1%
|
|
| 2016 | 6 |
2.2%
|
|
| 2017 | 4 |
1.5%
|
|
| 2018 | 7 |
2.6%
|
|
| 2019 | 3 |
1.1%
|
|
| 2020 | 1 |
0.4%
|
|
| 2021 | 4 |
1.5%
|
|
| 2022 | 6 |
2.2%
|
|
| 2023 | 1 |
0.4%
|