| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Does not apply | 1 | 
                                    
                                    0.9%
                                 | 
| 0 | No obstacle | 29 | 
                                    
                                    26.1%
                                 | 
| 1 | Minor obstacle | 35 | 
                                    
                                    31.5%
                                 | 
| 2 | Moderate obstacle | 17 | 
                                    
                                    15.3%
                                 | 
| 3 | Major obstacle | 21 | 
                                    
                                    18.9%
                                 | 
| 4 | Very severe obstacle | 8 | 
                                    
                                    7.2%
                                 |