| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 22 |
1.3%
|
| -7 | Does not apply is a floor in a building (spontaneous) | 406 |
24.4%
|
| 0 | 1220 |
73.4%
|
|
| 20 | 2 |
0.1%
|
|
| 30 | 1 |
0.1%
|
|
| 35 | 1 |
0.1%
|
|
| 50 | 2 |
0.1%
|
|
| 100 | 9 |
0.5%
|