| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 9 |
0.6%
|
| -7 | Does not apply | 14 |
1%
|
| 0 | No obstacle | 998 |
69%
|
| 1 | Minor obstacle | 256 |
17.7%
|
| 2 | Moderate obstacle | 126 |
8.7%
|
| 3 | Major obstacle | 28 |
1.9%
|
| 4 | Very severe obstacle | 15 |
1%
|