| Value | Category | Cases | |
|---|---|---|---|
| -99 | 1 | 
                                    
                                    0.3%
                                 | |
| 1 | Not effective at all | 2 | 
                                    
                                    0.7%
                                 | 
| 2 | 2 | 
                                    
                                    0.7%
                                 | |
| 3 | 8 | 
                                    
                                    2.7%
                                 | |
| 4 | 12 | 
                                    
                                    4.1%
                                 | |
| 5 | 34 | 
                                    
                                    11.6%
                                 | |
| 6 | 42 | 
                                    
                                    14.3%
                                 | |
| 7 | 49 | 
                                    
                                    16.7%
                                 | |
| 8 | 26 | 
                                    
                                    8.8%
                                 | |
| 9 | 16 | 
                                    
                                    5.4%
                                 | |
| 10 | Very effective | 6 | 
                                    
                                    2%
                                 | 
| 11 | Don't know | 96 | 
                                    
                                    32.7%
                                 | 
| Sysmiss | 7 |