| Value | Category | Cases | |
|---|---|---|---|
| 2007 | 7 |
12.3%
|
|
| 2008 | 19 |
33.3%
|
|
| 2009 | 16 |
28.1%
|
|
| 2010 | 15 |
26.3%
|
|
| 8888 | D/K Year | 0 |
0%
|
| 9999 | N/A | 0 |
0%
|
| Sysmiss | 1940 |