| Value | Category | Cases | |
|---|---|---|---|
| -2 | Refusal to answer | 0 |
0%
|
| -1 | Don't know | 0 |
0%
|
| 1982 | 1 |
20%
|
|
| 1983 | 1 |
20%
|
|
| 1990 | 1 |
20%
|
|
| 1994 | 1 |
20%
|
|
| 1999 | 1 |
20%
|