| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.2%
|
| -7 | Does not apply | 2 |
0.4%
|
| 0 | No obstacle | 399 |
75%
|
| 1 | Minor obstacle | 46 |
8.6%
|
| 2 | Moderate obstacle | 33 |
6.2%
|
| 3 | Major obstacle | 42 |
7.9%
|
| 4 | Very severe obstacle | 9 |
1.7%
|