| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.2%
|
| -7 | Does not apply | 4 |
1%
|
| 0 | No obstacle | 181 |
45%
|
| 1 | Minor obstacle | 66 |
16.4%
|
| 2 | Moderate obstacle | 73 |
18.2%
|
| 3 | Major obstacle | 47 |
11.7%
|
| 4 | Very severe obstacle | 30 |
7.5%
|