| Value | Category | Cases | |
|---|---|---|---|
| 1 | 1. More than 3 years | 0 |
0%
|
| 2 | 2. 1-3 years | 0 |
0%
|
| 3 | 3. 6 months - 1 year | 0 |
0%
|
| 4 | 4. 1-6 months | 0 |
0%
|
| 5 | 5. Less than a month | 1 |
4%
|
| 7 | 7. Not applicable | 21 |
84%
|
| 8 | 8. Refuse to answer | 3 |
12%
|
| Sysmiss | 74 |