| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.2%
|
| -7 | Does not apply | 2 |
0.1%
|
| 0 | No obstacle | 705 |
49.8%
|
| 1 | Minor obstacle | 246 |
17.4%
|
| 2 | Moderate obstacle | 150 |
10.6%
|
| 3 | Major obstacle | 117 |
8.3%
|
| 4 | Very severe obstacle | 193 |
13.6%
|