| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 |
1.1%
|
| -7 | Does not apply | 12 |
3.3%
|
| 0 | No obstacle | 255 |
70.2%
|
| 1 | Minor obstacle | 37 |
10.2%
|
| 2 | Moderate obstacle | 35 |
9.6%
|
| 3 | Major obstacle | 17 |
4.7%
|
| 4 | Very severe obstacle | 3 |
0.8%
|