| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 7 |
0.7%
|
| -7 | Does not apply | 5 |
0.5%
|
| 0 | No obstacle | 313 |
31.3%
|
| 1 | Minor obstacle | 303 |
30.3%
|
| 2 | Moderate obstacle | 219 |
21.9%
|
| 3 | Major obstacle | 128 |
12.8%
|
| 4 | Very severe obstacle | 26 |
2.6%
|