| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 | 
                                    
                                    2.7%
                                 | 
| -7 | Does not apply | 0 | 
                                    
                                    0%
                                 | 
| 0 | No obstacle | 31 | 
                                    
                                    27.9%
                                 | 
| 1 | Minor obstacle | 22 | 
                                    
                                    19.8%
                                 | 
| 2 | Moderate obstacle | 15 | 
                                    
                                    13.5%
                                 | 
| 3 | Major obstacle | 30 | 
                                    
                                    27%
                                 | 
| 4 | Very severe obstacle | 10 | 
                                    
                                    9%
                                 |