| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 53 |
4.4%
|
| 0 | No obstacle | 662 |
55.2%
|
| 1 | Minor obstacle | 174 |
14.5%
|
| 2 | Moderate obstacle | 154 |
12.8%
|
| 3 | Major obstacle | 101 |
8.4%
|
| 4 | Very severe obstacle | 55 |
4.6%
|