| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 5 |
0.6%
|
| -7 | Does not apply | 8 |
1%
|
| 0 | No obstacle | 479 |
62%
|
| 1 | Minor obstacle | 165 |
21.4%
|
| 2 | Moderate obstacle | 72 |
9.3%
|
| 3 | Major obstacle | 41 |
5.3%
|
| 4 | Very severe obstacle | 2 |
0.3%
|