| Value | Category | Cases | |
|---|---|---|---|
| 2000 | 2 |
20%
|
|
| 2011 | 1 |
10%
|
|
| 2012 | 2 |
20%
|
|
| 2013 | 1 |
10%
|
|
| 9998 | year don't know | 4 |
40%
|
| Sysmiss | 10906 |