| Value | Category | Cases | |
|---|---|---|---|
| -99 | Don't know | 0 | 
                                    
                                    0%
                                 | 
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| 10 | 10 | 
                                    
                                    50%
                                 | |
| 15 | 4 | 
                                    
                                    20%
                                 | |
| 20 | 3 | 
                                    
                                    15%
                                 | |
| 25 | 1 | 
                                    
                                    5%
                                 | |
| 30 | 2 | 
                                    
                                    10%
                                 | |
| Sysmiss | 340 |