| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Does not apply | 0 | 
                                    
                                    0%
                                 | 
| 0 | No obstacle | 189 | 
                                    
                                    52.1%
                                 | 
| 1 | Minor obstacle | 80 | 
                                    
                                    22%
                                 | 
| 2 | Moderate obstacle | 49 | 
                                    
                                    13.5%
                                 | 
| 3 | Major obstacle | 27 | 
                                    
                                    7.4%
                                 | 
| 4 | Very severe obstacle | 18 | 
                                    
                                    5%
                                 |