| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 14 |
1.7%
|
| 0 | No obstacle | 622 |
74.8%
|
| 1 | Minor obstacle | 123 |
14.8%
|
| 2 | Moderate obstacle | 48 |
5.8%
|
| 3 | Major obstacle | 17 |
2%
|
| 4 | Very severe obstacle | 6 |
0.7%
|