| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.6%
|
| -7 | Does not apply | 7 |
1.9%
|
| 0 | No obstacle | 271 |
75.3%
|
| 1 | Minor obstacle | 32 |
8.9%
|
| 2 | Moderate obstacle | 31 |
8.6%
|
| 3 | Major obstacle | 11 |
3.1%
|
| 4 | Very severe obstacle | 6 |
1.7%
|