| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    
| -7 | Does not apply | 1 | 
                                                                 
                                    
                                    0.2%
                                 
                                                             | 
                                                        
                    
| 0 | No obstacle | 170 | 
                                                                 
                                    
                                    28.7%
                                 
                                                             | 
                                                        
                    
| 1 | Minor obstacle | 64 | 
                                                                 
                                    
                                    10.8%
                                 
                                                             | 
                                                        
                    
| 2 | Moderate obstacle | 132 | 
                                                                 
                                    
                                    22.3%
                                 
                                                             | 
                                                        
                    
| 3 | Major obstacle | 148 | 
                                                                 
                                    
                                    25%
                                 
                                                             | 
                                                        
                    
| 4 | Very severe obstacle | 77 | 
                                                                 
                                    
                                    13%
                                 
                                                             |