| Value | Category | Cases | |
|---|---|---|---|
| -1 | Missing | 0 | 
                                    
                                    0%
                                 | 
| 1 | Impassable | 8 | 
                                    
                                    0.7%
                                 | 
| 2 | Very poor | 112 | 
                                    
                                    9.3%
                                 | 
| 3 | Poor | 176 | 
                                    
                                    14.7%
                                 | 
| 4 | Fair | 328 | 
                                    
                                    27.3%
                                 | 
| 5 | Good | 416 | 
                                    
                                    34.7%
                                 | 
| 6 | Very good | 160 | 
                                    
                                    13.3%
                                 |