| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 |
0%
|
| -7 | Does not apply | 1 |
0.1%
|
| 0 | No obstacle | 204 |
22.2%
|
| 1 | Minor obstacle | 300 |
32.6%
|
| 2 | Moderate obstacle | 241 |
26.2%
|
| 3 | Major obstacle | 113 |
12.3%
|
| 4 | Very severe obstacle | 60 |
6.5%
|