| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.2%
|
| -7 | Does not apply | 16 |
1.6%
|
| 0 | No obstacle | 646 |
66%
|
| 1 | Minor obstacle | 193 |
19.7%
|
| 2 | Moderate obstacle | 93 |
9.5%
|
| 3 | Major obstacle | 22 |
2.2%
|
| 4 | Very severe obstacle | 7 |
0.7%
|