| Value | Category | Cases | |
|---|---|---|---|
| 1 | flat | 458 | 
                                                                 
                                    
                                    55.4%
                                 
                                                             | 
                                                        
                    
| 2 | slightly sloped | 306 | 
                                                                 
                                    
                                    37%
                                 
                                                             | 
                                                        
                    
| 3 | very steep | 62 | 
                                                                 
                                    
                                    7.5%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 956 |