| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.2%
|
| -8 | 1 |
0.1%
|
|
| -7 | Does not apply | 4 |
0.4%
|
| 0 | No obstacle | 451 |
41.5%
|
| 1 | Minor obstacle | 192 |
17.7%
|
| 2 | Moderate obstacle | 258 |
23.8%
|
| 3 | Major obstacle | 120 |
11%
|
| 4 | Very severe obstacle | 58 |
5.3%
|