| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.5%
|
| -7 | Does not apply | 1 |
0.2%
|
| 0 | No obstacle | 158 |
36.8%
|
| 1 | Minor obstacle | 140 |
32.6%
|
| 2 | Moderate obstacle | 114 |
26.6%
|
| 3 | Major obstacle | 13 |
3%
|
| 4 | Very severe obstacle | 1 |
0.2%
|