| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 |
0.4%
|
| -7 | Does not apply | 5 |
0.5%
|
| 0 | No obstacle | 145 |
14.2%
|
| 1 | Minor obstacle | 125 |
12.3%
|
| 2 | Moderate obstacle | 177 |
17.4%
|
| 3 | Major obstacle | 231 |
22.7%
|
| 4 | Very severe obstacle | 332 |
32.6%
|