| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.2%
|
| -7 | Does not apply | 4 |
0.4%
|
| 0 | No obstacle | 211 |
21.4%
|
| 1 | Minor obstacle | 183 |
18.5%
|
| 2 | Moderate obstacle | 299 |
30.3%
|
| 3 | Major obstacle | 205 |
20.8%
|
| 4 | Very severe obstacle | 83 |
8.4%
|