| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 9 | 
                                    
                                    8.1%
                                 | 
| -7 | Does not apply | 3 | 
                                    
                                    2.7%
                                 | 
| 0 | No obstacle | 42 | 
                                    
                                    37.8%
                                 | 
| 1 | Minor obstacle | 29 | 
                                    
                                    26.1%
                                 | 
| 2 | Moderate obstacle | 13 | 
                                    
                                    11.7%
                                 | 
| 3 | Major obstacle | 10 | 
                                    
                                    9%
                                 | 
| 4 | Very severe obstacle | 5 | 
                                    
                                    4.5%
                                 |