| Value |
Category |
| -666 |
|
| 1 |
Grade 1 |
| 2 |
Grade 2 |
| 3 |
Grade 3 |
| 4 |
Grade 4 |
| 5 |
Grade 5 |
| 6 |
Grade 6 |
| 8 |
do not know |
| 9 |
not applicable |
| 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.