| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 6 |
0.6%
|
| -7 | Does not apply | 6 |
0.6%
|
| 0 | No obstacle | 516 |
52.7%
|
| 1 | Minor obstacle | 286 |
29.2%
|
| 2 | Moderate obstacle | 110 |
11.2%
|
| 3 | Major obstacle | 43 |
4.4%
|
| 4 | Very severe obstacle | 12 |
1.2%
|