| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 | 
                                                                 
                                    
                                    1%
                                 
                                                             | 
                                                        
                    
| -7 | Does not apply | 5 | 
                                                                 
                                    
                                    1.3%
                                 
                                                             | 
                                                        
                    
| 0 | No obstacle | 139 | 
                                                                 
                                    
                                    35.8%
                                 
                                                             | 
                                                        
                    
| 1 | Minor obstacle | 212 | 
                                                                 
                                    
                                    54.6%
                                 
                                                             | 
                                                        
                    
| 2 | Moderate obstacle | 24 | 
                                                                 
                                    
                                    6.2%
                                 
                                                             | 
                                                        
                    
| 3 | Major obstacle | 4 | 
                                                                 
                                    
                                    1%
                                 
                                                             | 
                                                        
                    
| 4 | Very severe obstacle | 0 | 
                                                                 
                                    
                                    0%
                                 
                                                             |