| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.2%
|
| -7 | Does not apply | 58 |
5.8%
|
| 0 | No obstacle | 610 |
60.6%
|
| 1 | Minor obstacle | 129 |
12.8%
|
| 2 | Moderate obstacle | 113 |
11.2%
|
| 3 | Major obstacle | 57 |
5.7%
|
| 4 | Very severe obstacle | 38 |
3.8%
|