| Value |
Category |
| -99 |
Don't know |
| -88 |
Refused |
| 1 |
Very easy |
| 2 |
Easy |
| 3 |
Difficult |
| 4 |
Very difficult |
| Missing value |
|
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.
