| Value | Category | Cases | |
|---|---|---|---|
| 1 | 2010-2012 | 132 |
24.8%
|
| 2 | 2007-2009 | 203 |
38.1%
|
| 3 | 2004-2006 | 89 |
16.7%
|
| 4 | 2001-2003 | 29 |
5.4%
|
| 5 | 1998-2000 | 33 |
6.2%
|
| 6 | Below 1997 | 45 |
8.4%
|
| 9 | Not specified | 2 |
0.4%
|
| Sysmiss | 1063 |