| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 18 |
0.2%
|
| -7 | Does not apply | 22 |
0.2%
|
| 0 | No obstacle | 4553 |
48.6%
|
| 1 | Minor obstacle | 2037 |
21.7%
|
| 2 | Moderate obstacle | 1511 |
16.1%
|
| 3 | Major obstacle | 976 |
10.4%
|
| 4 | Very severe obstacle | 259 |
2.8%
|