| Value | Category | Cases | |
|---|---|---|---|
| 1992 | 1 |
0.2%
|
|
| 1993 | 8 |
1.7%
|
|
| 1998 | 1 |
0.2%
|
|
| 1999 | 1 |
0.2%
|
|
| 2000 | 2 |
0.4%
|
|
| 2002 | 1 |
0.2%
|
|
| 2003 | 2 |
0.4%
|
|
| 2004 | 9 |
1.9%
|
|
| 2005 | 1 |
0.2%
|
|
| 2007 | 2 |
0.4%
|
|
| 2009 | 4 |
0.8%
|
|
| 2010 | 2 |
0.4%
|
|
| 2011 | 318 |
66.3%
|
|
| 2012 | 58 |
12.1%
|
|
| 2013 | 20 |
4.2%
|
|
| 2014 | 13 |
2.7%
|
|
| 2015 | 16 |
3.3%
|
|
| 2016 | 7 |
1.5%
|
|
| 2017 | 4 |
0.8%
|
|
| 2018 | 2 |
0.4%
|
|
| Missing value | 8 |
1.7%
|