| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.6%
|
| -7 | Does not apply | 1 |
0.3%
|
| 0 | No obstacle | 206 |
56.7%
|
| 1 | Minor obstacle | 48 |
13.2%
|
| 2 | Moderate obstacle | 72 |
19.8%
|
| 3 | Major obstacle | 28 |
7.7%
|
| 4 | Very severe obstacle | 6 |
1.7%
|