| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Does not apply | 6 | 
                                    
                                    1.7%
                                 | 
| 0 | No obstacle | 154 | 
                                    
                                    42.4%
                                 | 
| 1 | Minor obstacle | 87 | 
                                    
                                    24%
                                 | 
| 2 | Moderate obstacle | 68 | 
                                    
                                    18.7%
                                 | 
| 3 | Major obstacle | 34 | 
                                    
                                    9.4%
                                 | 
| 4 | Very severe obstacle | 14 | 
                                    
                                    3.9%
                                 |