| Value | Category |
|---|---|
| -3 | illegal missing |
| -2 | dont know |
| -1 | refuse |
| 1 | It was main use - more than 80% |
| 2 | It was important use - 60-80% |
| 3 | it was medium use - 40-60% |
| 4 | it was less important use - 20-40% |
| 5 | It was not significant use - Less than 20% |
| 6 | It was not used - 0% |
| Sysmiss |