| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 | 
                                                                 
                                    
                                    0.8%
                                 
                                                             | 
                                                        
                    
| -7 | Does not apply | 5 | 
                                                                 
                                    
                                    1.3%
                                 
                                                             | 
                                                        
                    
| 0 | No obstacle | 57 | 
                                                                 
                                    
                                    14.5%
                                 
                                                             | 
                                                        
                    
| 1 | Minor obstacle | 80 | 
                                                                 
                                    
                                    20.4%
                                 
                                                             | 
                                                        
                    
| 2 | Moderate obstacle | 81 | 
                                                                 
                                    
                                    20.7%
                                 
                                                             | 
                                                        
                    
| 3 | Major obstacle | 136 | 
                                                                 
                                    
                                    34.7%
                                 
                                                             | 
                                                        
                    
| 4 | Very severe obstacle | 30 | 
                                                                 
                                    
                                    7.7%
                                 
                                                             |