| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.2%
|
| -7 | Does not apply | 1 |
0.2%
|
| 0 | No obstacle | 125 |
20.1%
|
| 1 | Minor obstacle | 227 |
36.5%
|
| 2 | Moderate obstacle | 110 |
17.7%
|
| 3 | Major obstacle | 110 |
17.7%
|
| 4 | Very severe obstacle | 48 |
7.7%
|