| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 | 
                                                                 
                                    
                                    0.2%
                                 
                                                             | 
                                                        
                    
| -7 | Does not apply | 2 | 
                                                                 
                                    
                                    0.3%
                                 
                                                             | 
                                                        
                    
| 0 | No obstacle | 380 | 
                                                                 
                                    
                                    62.4%
                                 
                                                             | 
                                                        
                    
| 1 | Minor obstacle | 151 | 
                                                                 
                                    
                                    24.8%
                                 
                                                             | 
                                                        
                    
| 2 | Moderate obstacle | 56 | 
                                                                 
                                    
                                    9.2%
                                 
                                                             | 
                                                        
                    
| 3 | Major obstacle | 15 | 
                                                                 
                                    
                                    2.5%
                                 
                                                             | 
                                                        
                    
| 4 | Very severe obstacle | 4 | 
                                                                 
                                    
                                    0.7%
                                 
                                                             |