| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 | 
                                                                 
                                    
                                    0.2%
                                 
                                                             | 
                                                        
                    
| -7 | Does not apply | 12 | 
                                                                 
                                    
                                    1%
                                 
                                                             | 
                                                        
                    
| 0 | No obstacle | 519 | 
                                                                 
                                    
                                    42.7%
                                 
                                                             | 
                                                        
                    
| 1 | Minor obstacle | 266 | 
                                                                 
                                    
                                    21.9%
                                 
                                                             | 
                                                        
                    
| 2 | Moderate obstacle | 317 | 
                                                                 
                                    
                                    26.1%
                                 
                                                             | 
                                                        
                    
| 3 | Major obstacle | 75 | 
                                                                 
                                    
                                    6.2%
                                 
                                                             | 
                                                        
                    
| 4 | Very severe obstacle | 25 | 
                                                                 
                                    
                                    2.1%
                                 
                                                             |