| Value | Category | Cases | |
|---|---|---|---|
| 2007 | 3 |
0.9%
|
|
| 2008 | 19 |
5.9%
|
|
| 2009 | 22 |
6.9%
|
|
| 2010 | 124 |
38.6%
|
|
| 2011 | 139 |
43.3%
|
|
| 9997 | Inconsistent (Secondary Editing) | 2 |
0.6%
|
| 9999 | Missing | 12 |
3.7%
|
| Sysmiss | 4451 |