| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 5 |
0.8%
|
| -7 | Does not apply | 3 |
0.5%
|
| 0 | No obstacle | 494 |
80.7%
|
| 1 | Minor obstacle | 66 |
10.8%
|
| 2 | Moderate obstacle | 25 |
4.1%
|
| 3 | Major obstacle | 9 |
1.5%
|
| 4 | Very severe obstacle | 10 |
1.6%
|