| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 | 
                                    
                                    3.2%
                                 | 
| 0 | None | 29 | 
                                    
                                    46.8%
                                 | 
| 1 | 22 | 
                                    
                                    35.5%
                                 | |
| 2 | 8 | 
                                    
                                    12.9%
                                 | |
| 3 | 1 | 
                                    
                                    1.6%
                                 | |
| Sysmiss | 35 |