| Value | Category | Cases | |
|---|---|---|---|
| -1 | Missing | 1 |
0.1%
|
| 0 | Not at all effective | 88 |
7.3%
|
| 1 | Not very effective | 342 |
28.5%
|
| 2 | Somewhat effective | 299 |
24.9%
|
| 3 | Very effective | 187 |
15.6%
|
| 9 | Don't know | 283 |
23.6%
|
| 998 | Refused | 0 |
0%
|