| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.2%
|
| -7 | Does not apply | 23 |
1.3%
|
| 0 | No obstacle | 200 |
11.6%
|
| 1 | Minor obstacle | 200 |
11.6%
|
| 2 | Moderate obstacle | 234 |
13.6%
|
| 3 | Major obstacle | 544 |
31.5%
|
| 4 | Very severe obstacle | 521 |
30.2%
|