| Value | Category | Cases | |
|---|---|---|---|
| -99 | Don't know | 0 | 
                                    
                                    0%
                                 | 
| -9 | Don't know (spontaneous) | 8 | 
                                    
                                    3.7%
                                 | 
| 10 | 5 | 
                                    
                                    2.3%
                                 | |
| 15 | 1 | 
                                    
                                    0.5%
                                 | |
| 20 | 11 | 
                                    
                                    5%
                                 | |
| 25 | 3 | 
                                    
                                    1.4%
                                 | |
| 30 | 16 | 
                                    
                                    7.3%
                                 | |
| 33 | 1 | 
                                    
                                    0.5%
                                 | |
| 35 | 12 | 
                                    
                                    5.5%
                                 | |
| 40 | 27 | 
                                    
                                    12.3%
                                 | |
| 45 | 9 | 
                                    
                                    4.1%
                                 | |
| 50 | 73 | 
                                    
                                    33.3%
                                 | |
| 60 | 19 | 
                                    
                                    8.7%
                                 | |
| 65 | 1 | 
                                    
                                    0.5%
                                 | |
| 70 | 14 | 
                                    
                                    6.4%
                                 | |
| 80 | 4 | 
                                    
                                    1.8%
                                 | |
| 100 | 15 | 
                                    
                                    6.8%
                                 | |
| Sysmiss | 141 |