| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Does not apply | 1 | 
                                    
                                    0.5%
                                 | 
| 0 | No obstacle | 101 | 
                                    
                                    47%
                                 | 
| 1 | Minor obstacle | 46 | 
                                    
                                    21.4%
                                 | 
| 2 | Moderate obstacle | 23 | 
                                    
                                    10.7%
                                 | 
| 3 | Major obstacle | 25 | 
                                    
                                    11.6%
                                 | 
| 4 | Very severe obstacle | 19 | 
                                    
                                    8.8%
                                 |