| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 10 | 
                                    
                                    4.7%
                                 | 
| 0 | 187 | 
                                    
                                    87%
                                 | |
| 5 | 3 | 
                                    
                                    1.4%
                                 | |
| 7 | 1 | 
                                    
                                    0.5%
                                 | |
| 10 | 4 | 
                                    
                                    1.9%
                                 | |
| 15 | 1 | 
                                    
                                    0.5%
                                 | |
| 20 | 2 | 
                                    
                                    0.9%
                                 | |
| 30 | 4 | 
                                    
                                    1.9%
                                 | |
| 50 | 2 | 
                                    
                                    0.9%
                                 | |
| 70 | 1 | 
                                    
                                    0.5%
                                 |