| Value | Category | 
|---|---|
| 1 | 0 | 
| 2 | 99 | 
| 3 | 300 | 
| 4 | 400 | 
| 5 | 500 | 
| 6 | 600 | 
| 7 | 800 | 
| 8 | 1000 | 
| 9 | 1500 | 
| 10 | 2000 | 
| 11 | 2500 | 
| 12 | 2800 | 
| 13 | 3000 | 
| 14 | 4000 | 
| 15 | 4600 | 
| 16 | 5000 | 
| 17 | 15000 | 
| 18 | 25000 | 
| 19 | Don't know | 
| 20 | Refused to answer | 
| 21 | Outlier set to missing | 
| 22 | Inconsistency set to missing | 
| 23 | Not applicable |