| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.5%
|
| -7 | Does not apply | 1 |
0.2%
|
| 0 | No obstacle | 276 |
46.2%
|
| 1 | Minor obstacle | 105 |
17.6%
|
| 2 | Moderate obstacle | 103 |
17.2%
|
| 3 | Major obstacle | 80 |
13.4%
|
| 4 | Very severe obstacle | 30 |
5%
|