| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 |
0.4%
|
| -7 | Does not apply | 7 |
0.7%
|
| 0 | No obstacle | 526 |
52.5%
|
| 1 | Minor obstacle | 295 |
29.4%
|
| 2 | Moderate obstacle | 112 |
11.2%
|
| 3 | Major obstacle | 38 |
3.8%
|
| 4 | Very severe obstacle | 20 |
2%
|