| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.3%
|
| -7 | Does not apply | 11 |
1.7%
|
| 0 | No obstacle | 146 |
22.5%
|
| 1 | Minor obstacle | 40 |
6.2%
|
| 2 | Moderate obstacle | 56 |
8.6%
|
| 3 | Major obstacle | 151 |
23.3%
|
| 4 | Very severe obstacle | 243 |
37.4%
|