| Value | Category | Cases | |
|---|---|---|---|
| 2007 | 2 |
2.1%
|
|
| 2008 | 19 |
20%
|
|
| 2009 | 11 |
11.6%
|
|
| 2010 | 28 |
29.5%
|
|
| 2011 | 35 |
36.8%
|
|
| 9999 | Missing | 0 |
0%
|
| Sysmiss | 533 |