| Value | Category | Cases | |
|---|---|---|---|
| -99 | 1 | 
                                    
                                    0.7%
                                 | |
| 1 | Not effective at all | 2 | 
                                    
                                    1.5%
                                 | 
| 2 | 1 | 
                                    
                                    0.7%
                                 | |
| 3 | 6 | 
                                    
                                    4.5%
                                 | |
| 4 | 4 | 
                                    
                                    3%
                                 | |
| 5 | 26 | 
                                    
                                    19.4%
                                 | |
| 6 | 18 | 
                                    
                                    13.4%
                                 | |
| 7 | 15 | 
                                    
                                    11.2%
                                 | |
| 8 | 10 | 
                                    
                                    7.5%
                                 | |
| 9 | 7 | 
                                    
                                    5.2%
                                 | |
| 10 | Very effective | 8 | 
                                    
                                    6%
                                 | 
| 11 | Don't know | 36 | 
                                    
                                    26.9%
                                 |