| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 16 |
1.3%
|
| -7 | Does not apply | 9 |
0.7%
|
| 0 | No obstacle | 891 |
71.9%
|
| 1 | Minor obstacle | 115 |
9.3%
|
| 2 | Moderate obstacle | 119 |
9.6%
|
| 3 | Major obstacle | 60 |
4.8%
|
| 4 | Very severe obstacle | 29 |
2.3%
|