| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 | 
                                                                 
                                    
                                    0.3%
                                 
                                                             | 
                                                        
                    
| -7 | Does not apply | 22 | 
                                                                 
                                    
                                    5.6%
                                 
                                                             | 
                                                        
                    
| 0 | No obstacle | 146 | 
                                                                 
                                    
                                    37.2%
                                 
                                                             | 
                                                        
                    
| 1 | Minor obstacle | 114 | 
                                                                 
                                    
                                    29.1%
                                 
                                                             | 
                                                        
                    
| 2 | Moderate obstacle | 66 | 
                                                                 
                                    
                                    16.8%
                                 
                                                             | 
                                                        
                    
| 3 | Major obstacle | 39 | 
                                                                 
                                    
                                    9.9%
                                 
                                                             | 
                                                        
                    
| 4 | Very severe obstacle | 4 | 
                                                                 
                                    
                                    1%
                                 
                                                             |