| Value | Category | Cases | |
|---|---|---|---|
| 1 | Over one year. | 97 |
66%
|
| 2 | Under one year. | 47 |
32%
|
| 3 | I've never received negative results. | 3 |
2%
|
| 4 | Choose not to answer. | 0 |
0%
|
| Sysmiss | 214 |