| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know | 0 |
0%
|
| 1 | Less than one year | 0 |
0%
|
| 15 | 1 |
25%
|
|
| 17 | 1 |
25%
|
|
| 20 | 1 |
25%
|
|
| 24 | 1 |
25%
|