| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 6 |
0.6%
|
| -7 | Does not apply | 7 |
0.7%
|
| 0 | No obstacle | 415 |
42.4%
|
| 1 | Minor obstacle | 290 |
29.6%
|
| 2 | Moderate obstacle | 179 |
18.3%
|
| 3 | Major obstacle | 72 |
7.4%
|
| 4 | Very severe obstacle | 10 |
1%
|