| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 2 |
0.2%
|
| 0 | No obstacle | 106 |
8%
|
| 1 | Minor obstacle | 187 |
14.1%
|
| 2 | Moderate obstacle | 749 |
56.7%
|
| 3 | Major obstacle | 247 |
18.7%
|
| 4 | Very severe obstacle | 30 |
2.3%
|