| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Does not apply | 0 | 
                                    
                                    0%
                                 | 
| 0 | No obstacle | 284 | 
                                    
                                    78.2%
                                 | 
| 1 | Minor obstacle | 45 | 
                                    
                                    12.4%
                                 | 
| 2 | Moderate obstacle | 30 | 
                                    
                                    8.3%
                                 | 
| 3 | Major obstacle | 2 | 
                                    
                                    0.6%
                                 | 
| 4 | Very severe obstacle | 2 | 
                                    
                                    0.6%
                                 |