| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.2%
|
| -7 | Does not apply | 23 |
2.3%
|
| 0 | No obstacle | 337 |
33.3%
|
| 1 | Minor obstacle | 259 |
25.6%
|
| 2 | Moderate obstacle | 220 |
21.7%
|
| 3 | Major obstacle | 137 |
13.5%
|
| 4 | Very severe obstacle | 35 |
3.5%
|