| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Does not apply | 0 | 
                                    
                                    0%
                                 | 
| 0 | No obstacle | 113 | 
                                    
                                    31%
                                 | 
| 1 | Minor obstacle | 41 | 
                                    
                                    11.3%
                                 | 
| 2 | Moderate obstacle | 84 | 
                                    
                                    23.1%
                                 | 
| 3 | Major obstacle | 73 | 
                                    
                                    20.1%
                                 | 
| 4 | Very severe obstacle | 53 | 
                                    
                                    14.6%
                                 |