| Value | Category |
|---|---|
| 1 | Less than 25 litres (one container) |
| 2 | 25 to 100 litres (1 to 4 containers) |
| 3 | 101 to 200 litres (4 to 8 containers / ½ to 1 drum) |
| 4 | 201 to 400 litres (8 to 16 containers / 1 to 2 drums) |
| 5 | 401 to 600 litres (16 to 24 containers / 2 to 3 drums) |
| 6 | More than 600 litres / more than 3 drums |
| 8 | Do not know |
| 9 | Not applicable |