| Value | Category | Cases | |
|---|---|---|---|
| 2002 | 2 |
6.5%
|
|
| 2003 | 1 |
3.2%
|
|
| 2007 | 6 |
19.4%
|
|
| 2008 | 22 |
71%
|
|
| Sysmiss | 4348 |