| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 39 |
2.9%
|
| -7 | Does not apply is a floor in a building (spontaneous) | 308 |
23.3%
|
| 0 | 967 |
73.1%
|
|
| 20 | 3 |
0.2%
|
|
| 30 | 1 |
0.1%
|
|
| 50 | 1 |
0.1%
|
|
| 90 | 1 |
0.1%
|
|
| 100 | 3 |
0.2%
|