| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 |
0.2%
|
| -7 | Does not apply | 67 |
4%
|
| 0 | No obstacle | 445 |
26.8%
|
| 1 | Minor obstacle | 291 |
17.5%
|
| 2 | Moderate obstacle | 516 |
31%
|
| 3 | Major obstacle | 263 |
15.8%
|
| 4 | Very severe obstacle | 77 |
4.6%
|