| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.2%
|
| -7 | Does not apply | 1 |
0.2%
|
| 0 | No obstacle | 165 |
27.9%
|
| 1 | Minor obstacle | 30 |
5.1%
|
| 2 | Moderate obstacle | 76 |
12.8%
|
| 3 | Major obstacle | 144 |
24.3%
|
| 4 | Very severe obstacle | 175 |
29.6%
|