| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.2%
|
| -7 | Does not apply | 9 |
0.9%
|
| 0 | No obstacle | 237 |
23.3%
|
| 1 | Minor obstacle | 203 |
19.9%
|
| 2 | Moderate obstacle | 258 |
25.3%
|
| 3 | Major obstacle | 198 |
19.4%
|
| 4 | Very severe obstacle | 112 |
11%
|