| Value | Category | Cases | |
|---|---|---|---|
| 2006 | 1 |
0.4%
|
|
| 2007 | 6 |
2.2%
|
|
| 2008 | 15 |
5.5%
|
|
| 2009 | 31 |
11.3%
|
|
| 2010 | 77 |
28%
|
|
| 2011 | 135 |
49.1%
|
|
| 9997 | Inconsistent (Secondary Editing) | 1 |
0.4%
|
| 9999 | Missing | 9 |
3.3%
|
| Sysmiss | 4497 |