| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 | 
                                                                 
                                    
                                    0.9%
                                 
                                                             | 
                                                        
                    
| -7 | Does not apply | 10 | 
                                                                 
                                    
                                    4.3%
                                 
                                                             | 
                                                        
                    
| 0 | No obstacle | 185 | 
                                                                 
                                    
                                    79.4%
                                 
                                                             | 
                                                        
                    
| 1 | Minor obstacle | 17 | 
                                                                 
                                    
                                    7.3%
                                 
                                                             | 
                                                        
                    
| 2 | Moderate obstacle | 13 | 
                                                                 
                                    
                                    5.6%
                                 
                                                             | 
                                                        
                    
| 3 | Major obstacle | 5 | 
                                                                 
                                    
                                    2.1%
                                 
                                                             | 
                                                        
                    
| 4 | Very severe obstacle | 1 | 
                                                                 
                                    
                                    0.4%
                                 
                                                             |