| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 32 |
21.5%
|
| -7 | Does not apply is a floor in a building (spontaneous) | 25 |
16.8%
|
| 0 | 23 |
15.4%
|
|
| 20 | 3 |
2%
|
|
| 25 | 1 |
0.7%
|
|
| 30 | 4 |
2.7%
|
|
| 40 | 1 |
0.7%
|
|
| 50 | 4 |
2.7%
|
|
| 60 | 3 |
2%
|
|
| 70 | 1 |
0.7%
|
|
| 100 | 52 |
34.9%
|