| Value | Category | Cases | |
|---|---|---|---|
| 1 | months | 2 | 
                                    
                                    3.9%
                                 | 
| 2 | years | 38 | 
                                    
                                    74.5%
                                 | 
| 9 | special answers | 11 | 
                                    
                                    21.6%
                                 | 
| Sysmiss | 15300 |