| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.3%
|
| -7 | Does not apply | 1 |
0.3%
|
| 0 | No obstacle | 72 |
20%
|
| 1 | Minor obstacle | 104 |
28.9%
|
| 2 | Moderate obstacle | 115 |
31.9%
|
| 3 | Major obstacle | 52 |
14.4%
|
| 4 | Very severe obstacle | 15 |
4.2%
|