| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 | 
                                                                 
                                    
                                    0.7%
                                 
                                                             | 
                                                        
                    
| -7 | Does not apply | 15 | 
                                                                 
                                    
                                    2.5%
                                 
                                                             | 
                                                        
                    
| 0 | No obstacle | 114 | 
                                                                 
                                    
                                    19.1%
                                 
                                                             | 
                                                        
                    
| 1 | Minor obstacle | 116 | 
                                                                 
                                    
                                    19.4%
                                 
                                                             | 
                                                        
                    
| 2 | Moderate obstacle | 133 | 
                                                                 
                                    
                                    22.2%
                                 
                                                             | 
                                                        
                    
| 3 | Major obstacle | 171 | 
                                                                 
                                    
                                    28.6%
                                 
                                                             | 
                                                        
                    
| 4 | Very severe obstacle | 45 | 
                                                                 
                                    
                                    7.5%
                                 
                                                             |