| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 27 | 
                                    
                                    4.4%
                                 | 
| 0 | 575 | 
                                    
                                    94%
                                 | |
| 10 | 4 | 
                                    
                                    0.7%
                                 | |
| 20 | 3 | 
                                    
                                    0.5%
                                 | |
| 30 | 1 | 
                                    
                                    0.2%
                                 | |
| 44 | 1 | 
                                    
                                    0.2%
                                 | |
| 50 | 1 | 
                                    
                                    0.2%
                                 |