| Value | Category | Cases | |
|---|---|---|---|
| -99 | 2 | 
                                    
                                    1.5%
                                 | |
| 1 | Not effective at all | 3 | 
                                    
                                    2.2%
                                 | 
| 2 | 2 | 
                                    
                                    1.5%
                                 | |
| 3 | 2 | 
                                    
                                    1.5%
                                 | |
| 4 | 6 | 
                                    
                                    4.5%
                                 | |
| 5 | 20 | 
                                    
                                    14.9%
                                 | |
| 6 | 12 | 
                                    
                                    9%
                                 | |
| 7 | 25 | 
                                    
                                    18.7%
                                 | |
| 8 | 19 | 
                                    
                                    14.2%
                                 | |
| 9 | 6 | 
                                    
                                    4.5%
                                 | |
| 10 | Very effective | 4 | 
                                    
                                    3%
                                 | 
| 11 | Don't know | 33 | 
                                    
                                    24.6%
                                 |