| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| 35 | 1 | 
                                    
                                    25%
                                 | |
| 61 | 1 | 
                                    
                                    25%
                                 | |
| 170 | 1 | 
                                    
                                    25%
                                 | |
| 384 | 1 | 
                                    
                                    25%
                                 | |
| Sysmiss | 398 |