| Value | Category | Cases | |
|---|---|---|---|
| 1 | From 9 months to 5 years | 137 |
72.9%
|
| 2 | Every 6 months | 29 |
15.4%
|
| 88 | Other (specify:) | 1 |
0.5%
|
| 98 | Don?t know | 21 |
11.2%
|