| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.5%
|
| -7 | Does not apply | 2 |
0.5%
|
| 0 | No obstacle | 276 |
67.5%
|
| 1 | Minor obstacle | 58 |
14.2%
|
| 2 | Moderate obstacle | 46 |
11.2%
|
| 3 | Major obstacle | 17 |
4.2%
|
| 4 | Very severe obstacle | 8 |
2%
|