| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 7 |
0.5%
|
| -7 | Does not apply | 9 |
0.6%
|
| 0 | No obstacle | 893 |
63.1%
|
| 1 | Minor obstacle | 161 |
11.4%
|
| 2 | Moderate obstacle | 121 |
8.5%
|
| 3 | Major obstacle | 125 |
8.8%
|
| 4 | Very severe obstacle | 100 |
7.1%
|