| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.2%
|
| -7 | Does not apply | 4 |
0.7%
|
| 0 | No obstacle | 251 |
41.8%
|
| 1 | Minor obstacle | 193 |
32.1%
|
| 2 | Moderate obstacle | 93 |
15.5%
|
| 3 | Major obstacle | 45 |
7.5%
|
| 4 | Very severe obstacle | 14 |
2.3%
|