| Value | Category | Cases | |
|---|---|---|---|
| -98 | Don't know | 3 |
0.2%
|
| 1 | From birth | 6 |
0.4%
|
| 2 | After 1 month old | 3 |
0.2%
|
| 3 | After 3 months old | 35 |
2.2%
|
| 4 | After 6 months old | 1557 |
97.1%
|
| Sysmiss | 1553 |