| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    
| -7 | Does not apply | 4 | 
                                                                 
                                    
                                    1.7%
                                 
                                                             | 
                                                        
                    
| 0 | No obstacle | 113 | 
                                                                 
                                    
                                    48.5%
                                 
                                                             | 
                                                        
                    
| 1 | Minor obstacle | 12 | 
                                                                 
                                    
                                    5.2%
                                 
                                                             | 
                                                        
                    
| 2 | Moderate obstacle | 31 | 
                                                                 
                                    
                                    13.3%
                                 
                                                             | 
                                                        
                    
| 3 | Major obstacle | 46 | 
                                                                 
                                    
                                    19.7%
                                 
                                                             | 
                                                        
                    
| 4 | Very severe obstacle | 27 | 
                                                                 
                                    
                                    11.6%
                                 
                                                             |