| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.2%
|
| -7 | Never regiestered (spontaneous) | 0 |
0%
|
| 1887 | 1 |
0.2%
|
|
| 1928 | 1 |
0.2%
|
|
| 1956 | 1 |
0.2%
|
|
| 1958 | 1 |
0.2%
|
|
| 1965 | 1 |
0.2%
|
|
| 1969 | 1 |
0.2%
|
|
| 1970 | 1 |
0.2%
|
|
| 1987 | 1 |
0.2%
|
|
| 1988 | 1 |
0.2%
|
|
| 1989 | 3 |
0.5%
|
|
| 1990 | 2 |
0.3%
|
|
| 1991 | 1 |
0.2%
|
|
| 1992 | 4 |
0.7%
|
|
| 1993 | 4 |
0.7%
|
|
| 1994 | 7 |
1.2%
|
|
| 1995 | 11 |
1.9%
|
|
| 1996 | 20 |
3.4%
|
|
| 1997 | 15 |
2.6%
|
|
| 1998 | 12 |
2.1%
|
|
| 1999 | 9 |
1.5%
|
|
| 2000 | 12 |
2.1%
|
|
| 2001 | 12 |
2.1%
|
|
| 2002 | 10 |
1.7%
|
|
| 2003 | 10 |
1.7%
|
|
| 2004 | 18 |
3.1%
|
|
| 2005 | 22 |
3.8%
|
|
| 2006 | 24 |
4.1%
|
|
| 2007 | 28 |
4.8%
|
|
| 2008 | 34 |
5.9%
|
|
| 2009 | 27 |
4.6%
|
|
| 2010 | 27 |
4.6%
|
|
| 2011 | 33 |
5.7%
|
|
| 2012 | 41 |
7.1%
|
|
| 2013 | 31 |
5.3%
|
|
| 2014 | 27 |
4.6%
|
|
| 2015 | 37 |
6.4%
|
|
| 2016 | 41 |
7.1%
|
|
| 2017 | 33 |
5.7%
|
|
| 2018 | 16 |
2.8%
|