| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.2%
|
| -7 | Does not apply | 1 |
0.2%
|
| 0 | No obstacle | 329 |
54%
|
| 1 | Minor obstacle | 155 |
25.5%
|
| 2 | Moderate obstacle | 81 |
13.3%
|
| 3 | Major obstacle | 25 |
4.1%
|
| 4 | Very severe obstacle | 17 |
2.8%
|