| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 7 |
0.5%
|
| -7 | Does not apply | 5 |
0.4%
|
| 0 | No obstacle | 908 |
64.1%
|
| 1 | Minor obstacle | 213 |
15%
|
| 2 | Moderate obstacle | 113 |
8%
|
| 3 | Major obstacle | 103 |
7.3%
|
| 4 | Very severe obstacle | 67 |
4.7%
|