| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Does not apply | 1 | 
                                    
                                    0.3%
                                 | 
| 0 | No obstacle | 193 | 
                                    
                                    53%
                                 | 
| 1 | Minor obstacle | 58 | 
                                    
                                    15.9%
                                 | 
| 2 | Moderate obstacle | 71 | 
                                    
                                    19.5%
                                 | 
| 3 | Major obstacle | 23 | 
                                    
                                    6.3%
                                 | 
| 4 | Very severe obstacle | 18 | 
                                    
                                    4.9%
                                 |