| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 18 |
0.9%
|
| -7 | Does not apply | 6 |
0.3%
|
| 0 | No obstacle | 1640 |
82.2%
|
| 1 | Minor obstacle | 139 |
7%
|
| 2 | Moderate obstacle | 119 |
6%
|
| 3 | Major obstacle | 61 |
3.1%
|
| 4 | Very severe obstacle | 12 |
0.6%
|