| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.1%
|
| -7 | Does not apply | 8 |
0.6%
|
| 0 | No obstacle | 972 |
68.6%
|
| 1 | Minor obstacle | 191 |
13.5%
|
| 2 | Moderate obstacle | 142 |
10%
|
| 3 | Major obstacle | 73 |
5.2%
|
| 4 | Very severe obstacle | 28 |
2%
|