| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 13 | 
                                    
                                    0.9%
                                 | 
| -7 | Does not apply | 33 | 
                                    
                                    2.3%
                                 | 
| 0 | No obstacle | 1066 | 
                                    
                                    75.3%
                                 | 
| 1 | Minor obstacle | 128 | 
                                    
                                    9%
                                 | 
| 2 | Moderate obstacle | 75 | 
                                    
                                    5.3%
                                 | 
| 3 | Major obstacle | 66 | 
                                    
                                    4.7%
                                 | 
| 4 | Very severe obstacle | 35 | 
                                    
                                    2.5%
                                 |