| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 | 
                                                                 
                                    
                                    0.3%
                                 
                                                             | 
                                                        
                    
| -7 | Does not apply | 0 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    
| 0 | No obstacle | 55 | 
                                                                 
                                    
                                    14.2%
                                 
                                                             | 
                                                        
                    
| 1 | Minor obstacle | 168 | 
                                                                 
                                    
                                    43.3%
                                 
                                                             | 
                                                        
                    
| 2 | Moderate obstacle | 126 | 
                                                                 
                                    
                                    32.5%
                                 
                                                             | 
                                                        
                    
| 3 | Major obstacle | 37 | 
                                                                 
                                    
                                    9.5%
                                 
                                                             | 
                                                        
                    
| 4 | Very severe obstacle | 1 | 
                                                                 
                                    
                                    0.3%
                                 
                                                             |