| Value | Category | Cases | Weighted | |
|---|---|---|---|---|
| 1 | five-year system | 5835 | 8892030 |
24%
|
| 2 | six-year system | 16518 | 27907907 |
75.4%
|
| 3 | don't know | 144 | 232895 |
0.6%
|
| Sysmiss | 26689 | 43028549 |