| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 | 
                                    
                                    0.7%
                                 | 
| -7 | Does not apply | 0 | 
                                    
                                    0%
                                 | 
| 0 | No obstacle | 84 | 
                                    
                                    56%
                                 | 
| 1 | Minor obstacle | 43 | 
                                    
                                    28.7%
                                 | 
| 2 | Moderate obstacle | 7 | 
                                    
                                    4.7%
                                 | 
| 3 | Major obstacle | 12 | 
                                    
                                    8%
                                 | 
| 4 | Very severe obstacle | 3 | 
                                    
                                    2%
                                 |