| Value | Category | Cases | |
|---|---|---|---|
| -99 | 1 | 
                                    
                                    0.3%
                                 | |
| 1 | Not effective at all | 5 | 
                                    
                                    1.7%
                                 | 
| 2 | 7 | 
                                    
                                    2.4%
                                 | |
| 3 | 13 | 
                                    
                                    4.4%
                                 | |
| 4 | 20 | 
                                    
                                    6.8%
                                 | |
| 5 | 46 | 
                                    
                                    15.6%
                                 | |
| 6 | 18 | 
                                    
                                    6.1%
                                 | |
| 7 | 20 | 
                                    
                                    6.8%
                                 | |
| 8 | 16 | 
                                    
                                    5.4%
                                 | |
| 9 | 7 | 
                                    
                                    2.4%
                                 | |
| 10 | Very effective | 6 | 
                                    
                                    2%
                                 | 
| 11 | Don't know | 136 | 
                                    
                                    46.1%
                                 | 
| Sysmiss | 6 |