| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.2%
|
| -7 | Does not apply | 2 |
0.3%
|
| 0 | No obstacle | 123 |
20.5%
|
| 1 | Minor obstacle | 113 |
18.8%
|
| 2 | Moderate obstacle | 110 |
18.3%
|
| 3 | Major obstacle | 157 |
26.2%
|
| 4 | Very severe obstacle | 94 |
15.7%
|