| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 16 |
1.3%
|
| 1868 | 1 |
0.1%
|
|
| 1906 | 1 |
0.1%
|
|
| 1913 | 2 |
0.2%
|
|
| 1922 | 1 |
0.1%
|
|
| 1932 | 1 |
0.1%
|
|
| 1933 | 1 |
0.1%
|
|
| 1936 | 1 |
0.1%
|
|
| 1938 | 3 |
0.2%
|
|
| 1941 | 1 |
0.1%
|
|
| 1942 | 4 |
0.3%
|
|
| 1947 | 1 |
0.1%
|
|
| 1950 | 1 |
0.1%
|
|
| 1955 | 1 |
0.1%
|
|
| 1957 | 2 |
0.2%
|
|
| 1958 | 1 |
0.1%
|
|
| 1959 | 2 |
0.2%
|
|
| 1963 | 1 |
0.1%
|
|
| 1966 | 1 |
0.1%
|
|
| 1967 | 1 |
0.1%
|
|
| 1969 | 1 |
0.1%
|
|
| 1972 | 1 |
0.1%
|
|
| 1975 | 5 |
0.4%
|
|
| 1976 | 1 |
0.1%
|
|
| 1978 | 1 |
0.1%
|
|
| 1979 | 2 |
0.2%
|
|
| 1980 | 3 |
0.2%
|
|
| 1981 | 1 |
0.1%
|
|
| 1983 | 1 |
0.1%
|
|
| 1984 | 2 |
0.2%
|
|
| 1985 | 1 |
0.1%
|
|
| 1987 | 2 |
0.2%
|
|
| 1989 | 1 |
0.1%
|
|
| 1990 | 4 |
0.3%
|
|
| 1991 | 9 |
0.7%
|
|
| 1992 | 9 |
0.7%
|
|
| 1993 | 12 |
1%
|
|
| 1994 | 24 |
1.9%
|
|
| 1995 | 18 |
1.5%
|
|
| 1996 | 33 |
2.7%
|
|
| 1997 | 19 |
1.5%
|
|
| 1998 | 11 |
0.9%
|
|
| 1999 | 12 |
1%
|
|
| 2000 | 24 |
1.9%
|
|
| 2001 | 25 |
2%
|
|
| 2002 | 27 |
2.2%
|
|
| 2003 | 47 |
3.8%
|
|
| 2004 | 38 |
3.1%
|
|
| 2005 | 41 |
3.3%
|
|
| 2006 | 33 |
2.7%
|
|
| 2007 | 49 |
4%
|
|
| 2008 | 49 |
4%
|
|
| 2009 | 76 |
6.1%
|
|
| 2010 | 79 |
6.4%
|
|
| 2011 | 60 |
4.8%
|
|
| 2012 | 62 |
5%
|
|
| 2013 | 67 |
5.4%
|
|
| 2014 | 63 |
5.1%
|
|
| 2015 | 77 |
6.2%
|
|
| 2016 | 82 |
6.6%
|
|
| 2017 | 124 |
10%
|