| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 30 |
1.7%
|
| 0 | No obstacle | 743 |
43.1%
|
| 1 | Minor obstacle | 309 |
17.9%
|
| 2 | Moderate obstacle | 301 |
17.4%
|
| 3 | Major obstacle | 208 |
12.1%
|
| 4 | Very severe obstacle | 133 |
7.7%
|