| Value | Category | Cases | |
|---|---|---|---|
| 1 | Within the last 3 years | 16 |
1.6%
|
| 2 | 4-5 years ago | 2 |
0.2%
|
| 3 | more than 5 years ago | 4 |
0.4%
|
| 5 | Never had exam | 987 |
97.8%
|
| 8 | Do not know | 0 |
0%
|
| Sysmiss | 2929 |