| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 | 
                                    
                                    1.9%
                                 | 
| -7 | Does not apply | 3 | 
                                    
                                    1.4%
                                 | 
| 0 | No obstacle | 86 | 
                                    
                                    40%
                                 | 
| 1 | Minor obstacle | 47 | 
                                    
                                    21.9%
                                 | 
| 2 | Moderate obstacle | 36 | 
                                    
                                    16.7%
                                 | 
| 3 | Major obstacle | 29 | 
                                    
                                    13.5%
                                 | 
| 4 | Very severe obstacle | 10 | 
                                    
                                    4.7%
                                 |