| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.3%
|
| -7 | Does not apply | 4 |
1.1%
|
| 0 | No obstacle | 351 |
95.4%
|
| 1 | Minor obstacle | 6 |
1.6%
|
| 2 | Moderate obstacle | 4 |
1.1%
|
| 3 | Major obstacle | 1 |
0.3%
|
| 4 | Very severe obstacle | 1 |
0.3%
|