| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 13 | 
                                    
                                    1.5%
                                 | 
| 1 | Yes | 392 | 
                                    
                                    44.8%
                                 | 
| 2 | No | 470 | 
                                    
                                    53.7%
                                 | 
| Sysmiss | 123 |