| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 26 |
9.6%
|
| -7 | Does not apply is a floor in a building (spontaneous) | 8 |
3%
|
| 0 | 196 |
72.3%
|
|
| 20 | 2 |
0.7%
|
|
| 30 | 3 |
1.1%
|
|
| 50 | 4 |
1.5%
|
|
| 75 | 1 |
0.4%
|
|
| 80 | 1 |
0.4%
|
|
| 100 | 30 |
11.1%
|