| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.2%
|
| -7 | Does not apply | 21 |
1.5%
|
| 0 | No obstacle | 984 |
69.5%
|
| 1 | Minor obstacle | 159 |
11.2%
|
| 2 | Moderate obstacle | 92 |
6.5%
|
| 3 | Major obstacle | 96 |
6.8%
|
| 4 | Very severe obstacle | 61 |
4.3%
|