| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.2%
|
| -7 | Does not apply | 5 |
0.8%
|
| 0 | No obstacle | 115 |
19.1%
|
| 1 | Minor obstacle | 156 |
25.9%
|
| 2 | Moderate obstacle | 124 |
20.6%
|
| 3 | Major obstacle | 128 |
21.2%
|
| 4 | Very severe obstacle | 74 |
12.3%
|