| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 37 | 
                                    
                                    3%
                                 | 
| -7 | Does not apply | 47 | 
                                    
                                    3.8%
                                 | 
| 0 | No obstacle | 922 | 
                                    
                                    74.4%
                                 | 
| 1 | Minor obstacle | 75 | 
                                    
                                    6.1%
                                 | 
| 2 | Moderate obstacle | 63 | 
                                    
                                    5.1%
                                 | 
| 3 | Major obstacle | 49 | 
                                    
                                    4%
                                 | 
| 4 | Very severe obstacle | 46 | 
                                    
                                    3.7%
                                 |