| Value |
Category |
| 1 |
never |
| 2 |
before 1970 |
| 3 |
1970-74 |
| 4 |
1975-79 |
| 5 |
1980-84 |
| 6 |
1985-89 |
| 7 |
since 1990 |
| Sysmiss |
|
Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.