| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.3%
|
| -7 | Does not apply | 5 |
0.5%
|
| 0 | No obstacle | 216 |
21.1%
|
| 1 | Minor obstacle | 170 |
16.6%
|
| 2 | Moderate obstacle | 235 |
22.9%
|
| 3 | Major obstacle | 258 |
25.2%
|
| 4 | Very severe obstacle | 138 |
13.5%
|