| Value | Category | Cases | |
|---|---|---|---|
| 1 | Necessary | 6245 | 
                                                                 
                                    
                                    61%
                                 
                                                             | 
                                                        
                    
| 2 | Unnecessary | 2220 | 
                                                                 
                                    
                                    21.7%
                                 
                                                             | 
                                                        
                    
| 3 | Don't know | 1780 | 
                                                                 
                                    
                                    17.4%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 671 |