| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.7%
|
| -7 | Does not apply | 9 |
2.1%
|
| 0 | No obstacle | 115 |
26.8%
|
| 1 | Minor obstacle | 108 |
25.2%
|
| 2 | Moderate obstacle | 164 |
38.2%
|
| 3 | Major obstacle | 26 |
6.1%
|
| 4 | Very severe obstacle | 4 |
0.9%
|