| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.2%
|
| -7 | Does not apply | 2 |
0.3%
|
| 0 | No obstacle | 183 |
29.8%
|
| 1 | Minor obstacle | 144 |
23.4%
|
| 2 | Moderate obstacle | 129 |
21%
|
| 3 | Major obstacle | 122 |
19.8%
|
| 4 | Very severe obstacle | 34 |
5.5%
|