| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.3%
|
| -7 | Does not apply | 1 |
0.3%
|
| 0 | No obstacle | 35 |
11.5%
|
| 1 | Minor obstacle | 17 |
5.6%
|
| 2 | Moderate obstacle | 36 |
11.8%
|
| 3 | Major obstacle | 85 |
27.9%
|
| 4 | Very severe obstacle | 130 |
42.6%
|