| Value | Category | Cases | |
|---|---|---|---|
| -99 | 1 | 
                                    
                                    0.3%
                                 | |
| 1 | Not effective at all | 3 | 
                                    
                                    1%
                                 | 
| 2 | 2 | 
                                    
                                    0.7%
                                 | |
| 3 | 20 | 
                                    
                                    6.8%
                                 | |
| 4 | 16 | 
                                    
                                    5.5%
                                 | |
| 5 | 56 | 
                                    
                                    19.2%
                                 | |
| 6 | 29 | 
                                    
                                    9.9%
                                 | |
| 7 | 22 | 
                                    
                                    7.5%
                                 | |
| 8 | 12 | 
                                    
                                    4.1%
                                 | |
| 9 | 8 | 
                                    
                                    2.7%
                                 | |
| 10 | Very effective | 2 | 
                                    
                                    0.7%
                                 | 
| 11 | Don't know | 121 | 
                                    
                                    41.4%
                                 | 
| Sysmiss | 9 |