| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 9 |
0.9%
|
| 0 | No obstacle | 235 |
23.2%
|
| 1 | Minor obstacle | 281 |
27.7%
|
| 2 | Moderate obstacle | 264 |
26.1%
|
| 3 | Major obstacle | 172 |
17%
|
| 4 | Very severe obstacle | 51 |
5%
|