| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.3%
|
| -7 | Does not apply | 73 |
7.3%
|
| 0 | No obstacle | 502 |
50.1%
|
| 1 | Minor obstacle | 166 |
16.6%
|
| 2 | Moderate obstacle | 117 |
11.7%
|
| 3 | Major obstacle | 121 |
12.1%
|
| 4 | Very severe obstacle | 19 |
1.9%
|