| Value | Category | Cases | |
|---|---|---|---|
| 2001 | 2 |
1.5%
|
|
| 2002 | 2 |
1.5%
|
|
| 2003 | 21 |
16.2%
|
|
| 2004 | 26 |
20%
|
|
| 2005 | 28 |
21.5%
|
|
| 2006 | 28 |
21.5%
|
|
| 2007 | 23 |
17.7%
|
|
| Sysmiss | 76 |