| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.2%
|
| -7 | Does not apply | 30 |
2.1%
|
| 0 | No obstacle | 973 |
68.7%
|
| 1 | Minor obstacle | 152 |
10.7%
|
| 2 | Moderate obstacle | 83 |
5.9%
|
| 3 | Major obstacle | 94 |
6.6%
|
| 4 | Very severe obstacle | 81 |
5.7%
|