| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 | 
                                                                 
                                    
                                    0.4%
                                 
                                                             | 
                                                        
                    
| -7 | Does not apply | 4 | 
                                                                 
                                    
                                    1.7%
                                 
                                                             | 
                                                        
                    
| 0 | No obstacle | 133 | 
                                                                 
                                    
                                    57.1%
                                 
                                                             | 
                                                        
                    
| 1 | Minor obstacle | 30 | 
                                                                 
                                    
                                    12.9%
                                 
                                                             | 
                                                        
                    
| 2 | Moderate obstacle | 25 | 
                                                                 
                                    
                                    10.7%
                                 
                                                             | 
                                                        
                    
| 3 | Major obstacle | 33 | 
                                                                 
                                    
                                    14.2%
                                 
                                                             | 
                                                        
                    
| 4 | Very severe obstacle | 7 | 
                                                                 
                                    
                                    3%
                                 
                                                             |