| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 53 | 
                                    
                                    8.3%
                                 | 
| 0 | 258 | 
                                    
                                    40.3%
                                 | |
| 1 | 134 | 
                                    
                                    20.9%
                                 | |
| 2 | 55 | 
                                    
                                    8.6%
                                 | |
| 3 | 37 | 
                                    
                                    5.8%
                                 | |
| 4 | 18 | 
                                    
                                    2.8%
                                 | |
| 5 | 44 | 
                                    
                                    6.9%
                                 | |
| 6 | 1 | 
                                    
                                    0.2%
                                 | |
| 7 | 3 | 
                                    
                                    0.5%
                                 | |
| 8 | 1 | 
                                    
                                    0.2%
                                 | |
| 10 | 12 | 
                                    
                                    1.9%
                                 | |
| 13 | 1 | 
                                    
                                    0.2%
                                 | |
| 15 | 10 | 
                                    
                                    1.6%
                                 | |
| 20 | 9 | 
                                    
                                    1.4%
                                 | |
| 25 | 2 | 
                                    
                                    0.3%
                                 | |
| 30 | 2 | 
                                    
                                    0.3%
                                 | |
| Sysmiss | 776 |