| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 13 | 
                                    
                                    7.4%
                                 | 
| 0 | None | 130 | 
                                    
                                    74.3%
                                 | 
| 1 | 10 | 
                                    
                                    5.7%
                                 | |
| 2 | 2 | 
                                    
                                    1.1%
                                 | |
| 3 | 3 | 
                                    
                                    1.7%
                                 | |
| 5 | 7 | 
                                    
                                    4%
                                 | |
| 8 | 1 | 
                                    
                                    0.6%
                                 | |
| 10 | 3 | 
                                    
                                    1.7%
                                 | |
| 15 | 2 | 
                                    
                                    1.1%
                                 | |
| 20 | 4 | 
                                    
                                    2.3%
                                 | |
| Sysmiss | 40 |