| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 9 | 
                                    
                                    8.1%
                                 | 
| -7 | Does not apply | 1 | 
                                    
                                    0.9%
                                 | 
| 0 | No obstacle | 43 | 
                                    
                                    38.7%
                                 | 
| 1 | Minor obstacle | 40 | 
                                    
                                    36%
                                 | 
| 2 | Moderate obstacle | 9 | 
                                    
                                    8.1%
                                 | 
| 3 | Major obstacle | 8 | 
                                    
                                    7.2%
                                 | 
| 4 | Very severe obstacle | 1 | 
                                    
                                    0.9%
                                 |