| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 8 |
0.6%
|
| -7 | Does not apply | 6 |
0.5%
|
| 0 | No obstacle | 209 |
16.1%
|
| 1 | Minor obstacle | 291 |
22.4%
|
| 2 | Moderate obstacle | 230 |
17.7%
|
| 3 | Major obstacle | 224 |
17.2%
|
| 4 | Very severe obstacle | 332 |
25.5%
|