| Value | Category | Cases | |
|---|---|---|---|
| -99 | 1 | 
                                    
                                    0.7%
                                 | |
| 1 | Not effective at all | 1 | 
                                    
                                    0.7%
                                 | 
| 2 | 1 | 
                                    
                                    0.7%
                                 | |
| 3 | 4 | 
                                    
                                    3%
                                 | |
| 4 | 11 | 
                                    
                                    8.2%
                                 | |
| 5 | 22 | 
                                    
                                    16.4%
                                 | |
| 6 | 19 | 
                                    
                                    14.2%
                                 | |
| 7 | 18 | 
                                    
                                    13.4%
                                 | |
| 8 | 5 | 
                                    
                                    3.7%
                                 | |
| 9 | 8 | 
                                    
                                    6%
                                 | |
| 10 | Very effective | 11 | 
                                    
                                    8.2%
                                 | 
| 11 | Don't know | 33 | 
                                    
                                    24.6%
                                 |