| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 8 |
2.3%
|
| -7 | Does not apply | 12 |
3.4%
|
| 0 | No obstacle | 304 |
86.6%
|
| 1 | Minor obstacle | 18 |
5.1%
|
| 2 | Moderate obstacle | 6 |
1.7%
|
| 3 | Major obstacle | 2 |
0.6%
|
| 4 | Very severe obstacle | 1 |
0.3%
|