| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 12 |
1.4%
|
| 0 | No obstacle | 399 |
46.9%
|
| 1 | Minor obstacle | 192 |
22.6%
|
| 2 | Moderate obstacle | 147 |
17.3%
|
| 3 | Major obstacle | 66 |
7.8%
|
| 4 | Very severe obstacle | 33 |
3.9%
|