| Value | Category | Cases | |
|---|---|---|---|
| 1 | Annual | 33 |
32.4%
|
| 2 | Every 2 years | 12 |
11.8%
|
| 3 | Every 3 years | 45 |
44.1%
|
| 9 | Other (specify)____ | 12 |
11.8%
|
| Sysmiss | 98 |