| Value | Category | Cases | |
|---|---|---|---|
| 1 | Less than 1 year | 4 |
0.2%
|
| 2 | 1 to 3 years | 124 |
6.3%
|
| 3 | 4 to 10 years | 695 |
35.2%
|
| 4 | 10 to 20 years | 653 |
33.1%
|
| 5 | Many generations | 498 |
25.2%
|
| Sysmiss | 3343 |