| Value | Category | Cases | |
|---|---|---|---|
| 1 | Not effective at all | 1 | 
                                    
                                    0.7%
                                 | 
| 2 | 1 | 
                                    
                                    0.7%
                                 | |
| 3 | 2 | 
                                    
                                    1.5%
                                 | |
| 4 | 7 | 
                                    
                                    5.2%
                                 | |
| 5 | 20 | 
                                    
                                    14.9%
                                 | |
| 6 | 13 | 
                                    
                                    9.7%
                                 | |
| 7 | 28 | 
                                    
                                    20.9%
                                 | |
| 8 | 14 | 
                                    
                                    10.4%
                                 | |
| 9 | 1 | 
                                    
                                    0.7%
                                 | |
| 10 | Very effective | 7 | 
                                    
                                    5.2%
                                 | 
| 11 | Don't know | 40 | 
                                    
                                    29.9%
                                 |