| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.1%
|
| -7 | Does not apply | 74 |
3.6%
|
| 0 | No obstacle | 1284 |
62.1%
|
| 1 | Minor obstacle | 192 |
9.3%
|
| 2 | Moderate obstacle | 231 |
11.2%
|
| 3 | Major obstacle | 232 |
11.2%
|
| 4 | Very severe obstacle | 54 |
2.6%
|