| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 | 
                                                                 
                                    
                                    0.8%
                                 
                                                             | 
                                                        
                    
| -7 | Does not apply | 13 | 
                                                                 
                                    
                                    3.6%
                                 
                                                             | 
                                                        
                    
| 0 | No obstacle | 144 | 
                                                                 
                                    
                                    39.6%
                                 
                                                             | 
                                                        
                    
| 1 | Minor obstacle | 86 | 
                                                                 
                                    
                                    23.6%
                                 
                                                             | 
                                                        
                    
| 2 | Moderate obstacle | 67 | 
                                                                 
                                    
                                    18.4%
                                 
                                                             | 
                                                        
                    
| 3 | Major obstacle | 39 | 
                                                                 
                                    
                                    10.7%
                                 
                                                             | 
                                                        
                    
| 4 | Very severe obstacle | 12 | 
                                                                 
                                    
                                    3.3%
                                 
                                                             |