| Value | Category | Cases | |
|---|---|---|---|
| 1 | flat | 120 | 
                                                                 
                                    
                                    59.7%
                                 
                                                             | 
                                                        
                    
| 2 | slightly sloped | 71 | 
                                                                 
                                    
                                    35.3%
                                 
                                                             | 
                                                        
                    
| 3 | very steep | 10 | 
                                                                 
                                    
                                    5%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 1581 |