| Value |
Category |
| 1 |
1 yr or less |
| 2 |
between 1 and 2 yrs |
| 3 |
more than 2 yrs |
| 4 |
never |
| 77 |
don't know |
| 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.