| Value | Category | Cases | |
|---|---|---|---|
| -99 | Don't know | 0 | 
                                    
                                    0%
                                 | 
| -9 | Don't know (spontaneous) | 1 | 
                                    
                                    0.4%
                                 | 
| 0 | 1 | 
                                    
                                    0.4%
                                 | |
| 10 | 1 | 
                                    
                                    0.4%
                                 | |
| 15 | 2 | 
                                    
                                    0.9%
                                 | |
| 20 | 14 | 
                                    
                                    6.3%
                                 | |
| 25 | 7 | 
                                    
                                    3.1%
                                 | |
| 30 | 33 | 
                                    
                                    14.7%
                                 | |
| 35 | 23 | 
                                    
                                    10.3%
                                 | |
| 40 | 67 | 
                                    
                                    29.9%
                                 | |
| 45 | 16 | 
                                    
                                    7.1%
                                 | |
| 50 | 23 | 
                                    
                                    10.3%
                                 | |
| 55 | 9 | 
                                    
                                    4%
                                 | |
| 60 | 17 | 
                                    
                                    7.6%
                                 | |
| 65 | 2 | 
                                    
                                    0.9%
                                 | |
| 70 | 4 | 
                                    
                                    1.8%
                                 | |
| 75 | 1 | 
                                    
                                    0.4%
                                 | |
| 80 | 3 | 
                                    
                                    1.3%
                                 | |
| Sysmiss | 136 |