| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 | 
                                    
                                    2.9%
                                 | 
| 0 | None | 56 | 
                                    
                                    80%
                                 | 
| 1 | 11 | 
                                    
                                    15.7%
                                 | |
| 2 | 1 | 
                                    
                                    1.4%
                                 | |
| Sysmiss | 332 |