| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 |
0.7%
|
| -7 | Does not apply | 3 |
0.5%
|
| 0 | No obstacle | 470 |
76.8%
|
| 1 | Minor obstacle | 70 |
11.4%
|
| 2 | Moderate obstacle | 39 |
6.4%
|
| 3 | Major obstacle | 14 |
2.3%
|
| 4 | Very severe obstacle | 12 |
2%
|