| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 5 |
1%
|
| -7 | Does not apply | 1 |
0.2%
|
| 0 | No obstacle | 247 |
51.5%
|
| 1 | Minor obstacle | 121 |
25.2%
|
| 2 | Moderate obstacle | 58 |
12.1%
|
| 3 | Major obstacle | 34 |
7.1%
|
| 4 | Very severe obstacle | 14 |
2.9%
|