| Value | Category | Cases | |
|---|---|---|---|
| 1 | less than 2 months | 2941 |
12.4%
|
| 2 | 12 - 23 months | 1160 |
4.9%
|
| 3 | 2 years | 3962 |
16.7%
|
| 9 | missing | 58 |
0.2%
|
| Sysmiss | 15595 |
65.8%
|