| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 0 |
0%
|
| 0 | No obstacle | 155 |
15.7%
|
| 1 | Minor obstacle | 256 |
25.9%
|
| 2 | Moderate obstacle | 278 |
28.2%
|
| 3 | Major obstacle | 206 |
20.9%
|
| 4 | Very severe obstacle | 91 |
9.2%
|