| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.3%
|
| -7 | Does not apply | 0 | |
| 0 | No obstacle | 77 |
21.4%
|
| 1 | Minor obstacle | 105 |
29.2%
|
| 2 | Moderate obstacle | 117 |
32.5%
|
| 3 | Major obstacle | 52 |
14.4%
|
| 4 | Very severe obstacle | 8 |
2.2%
|