| Value | Category | Cases | |
|---|---|---|---|
| 1 | 2010-2012 | 446 |
34%
|
| 2 | 2007-2009 | 366 |
27.9%
|
| 3 | 2004-2006 | 177 |
13.5%
|
| 4 | 2001-2003 | 64 |
4.9%
|
| 5 | 1998-2000 | 47 |
3.6%
|
| 6 | Below 1997 | 67 |
5.1%
|
| 9 | Not specified | 145 |
11.1%
|
| Sysmiss | 284 |