| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Does not apply | 0 | 
                                    
                                    0%
                                 | 
| 0 | No obstacle | 125 | 
                                    
                                    31.1%
                                 | 
| 1 | Minor obstacle | 88 | 
                                    
                                    21.9%
                                 | 
| 2 | Moderate obstacle | 114 | 
                                    
                                    28.4%
                                 | 
| 3 | Major obstacle | 45 | 
                                    
                                    11.2%
                                 | 
| 4 | Very severe obstacle | 30 | 
                                    
                                    7.5%
                                 |