| Value |
Category |
| 1 |
Less than month ago |
| 2 |
1-3 months ago |
| 3 |
4-6 months ago |
| 4 |
More than 6 months ago |
| 5 |
Never measured |
| 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.