| Value | Category | Cases | |
|---|---|---|---|
| 1 | Before 1945 | 270 |
7.5%
|
| 2 | 1945-1960 | 440 |
12.2%
|
| 3 | 1961-1980 | 1195 |
33.2%
|
| 4 | 1981-1990 | 885 |
24.6%
|
| 5 | After 1990 | 809 |
22.5%
|