| Value |
Category |
| 1 |
Once a year |
| 2 |
Twice a year |
| 3 |
Less than once a yea |
| 4 |
When requested by do |
| 5 |
Has had only once |
| 8 |
Do not remember |
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.