| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.3%
|
| -7 | Does not apply | 6 |
1.6%
|
| 0 | No obstacle | 279 |
76.6%
|
| 1 | Minor obstacle | 35 |
9.6%
|
| 2 | Moderate obstacle | 28 |
7.7%
|
| 3 | Major obstacle | 8 |
2.2%
|
| 4 | Very severe obstacle | 7 |
1.9%
|