| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.3%
|
| -7 | Does not apply | 1 |
0.3%
|
| 0 | No obstacle | 229 |
73.6%
|
| 1 | Minor obstacle | 23 |
7.4%
|
| 2 | Moderate obstacle | 27 |
8.7%
|
| 3 | Major obstacle | 21 |
6.8%
|
| 4 | Very severe obstacle | 9 |
2.9%
|