| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.2%
|
| -7 | Does not apply | 7 |
0.7%
|
| 0 | No obstacle | 273 |
26.8%
|
| 1 | Minor obstacle | 155 |
15.2%
|
| 2 | Moderate obstacle | 206 |
20.2%
|
| 3 | Major obstacle | 266 |
26.1%
|
| 4 | Very severe obstacle | 110 |
10.8%
|