| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 6 | 
                                                                 
                                    
                                    0.5%
                                 
                                                             | 
                                                        
                    
| -7 | Does not apply | 20 | 
                                                                 
                                    
                                    1.6%
                                 
                                                             | 
                                                        
                    
| 0 | No obstacle | 933 | 
                                                                 
                                    
                                    76.7%
                                 
                                                             | 
                                                        
                    
| 1 | Minor obstacle | 116 | 
                                                                 
                                    
                                    9.5%
                                 
                                                             | 
                                                        
                    
| 2 | Moderate obstacle | 87 | 
                                                                 
                                    
                                    7.2%
                                 
                                                             | 
                                                        
                    
| 3 | Major obstacle | 32 | 
                                                                 
                                    
                                    2.6%
                                 
                                                             | 
                                                        
                    
| 4 | Very severe obstacle | 22 | 
                                                                 
                                    
                                    1.8%
                                 
                                                             |