| Value | Category | Cases | |
|---|---|---|---|
| -99 | Don't know | 0 | 
                                    
                                    0%
                                 | 
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| 0 | 18 | 
                                    
                                    72%
                                 | |
| 1 | 1 | 
                                    
                                    4%
                                 | |
| 2 | 2 | 
                                    
                                    8%
                                 | |
| 5 | 1 | 
                                    
                                    4%
                                 | |
| 12 | 1 | 
                                    
                                    4%
                                 | |
| 15 | 2 | 
                                    
                                    8%
                                 | |
| Sysmiss | 217 |