| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 | 
                                                                 
                                    
                                    0.5%
                                 
                                                             | 
                                                        
                    
| -7 | Does not apply | 19 | 
                                                                 
                                    
                                    5%
                                 
                                                             | 
                                                        
                    
| 0 | No obstacle | 18 | 
                                                                 
                                    
                                    4.7%
                                 
                                                             | 
                                                        
                    
| 1 | Minor obstacle | 67 | 
                                                                 
                                    
                                    17.6%
                                 
                                                             | 
                                                        
                    
| 2 | Moderate obstacle | 84 | 
                                                                 
                                    
                                    22.1%
                                 
                                                             | 
                                                        
                    
| 3 | Major obstacle | 138 | 
                                                                 
                                    
                                    36.3%
                                 
                                                             | 
                                                        
                    
| 4 | Very severe obstacle | 52 | 
                                                                 
                                    
                                    13.7%
                                 
                                                             |