| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.2%
|
| -7 | Does not apply | 8 |
0.8%
|
| 0 | No obstacle | 222 |
21.9%
|
| 1 | Minor obstacle | 224 |
22.1%
|
| 2 | Moderate obstacle | 347 |
34.3%
|
| 3 | Major obstacle | 167 |
16.5%
|
| 4 | Very severe obstacle | 43 |
4.2%
|