| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.5%
|
| -7 | Does not apply | 9 |
1.5%
|
| 0 | No obstacle | 144 |
24%
|
| 1 | Minor obstacle | 115 |
19.2%
|
| 2 | Moderate obstacle | 99 |
16.5%
|
| 3 | Major obstacle | 139 |
23.2%
|
| 4 | Very severe obstacle | 91 |
15.2%
|