| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.2%
|
| -7 | Does not apply | 6 |
0.6%
|
| 0 | No obstacle | 277 |
27.2%
|
| 1 | Minor obstacle | 157 |
15.4%
|
| 2 | Moderate obstacle | 201 |
19.7%
|
| 3 | Major obstacle | 213 |
20.9%
|
| 4 | Very severe obstacle | 163 |
16%
|