| Value | Category | Cases | |
|---|---|---|---|
| 0 | not given | 406 | 
                                    
                                    84.8%
                                 | 
| 1996 | 1 | 
                                    
                                    0.2%
                                 | |
| 1997 | 1 | 
                                    
                                    0.2%
                                 | |
| 1998 | 1 | 
                                    
                                    0.2%
                                 | |
| 1999 | 2 | 
                                    
                                    0.4%
                                 | |
| 2000 | 1 | 
                                    
                                    0.2%
                                 | |
| 4444 | marked on card | 30 | 
                                    
                                    6.3%
                                 | 
| 6666 | mother reported | 37 | 
                                    
                                    7.7%
                                 | 
| 9997 | inconsistent | 0 | 
                                    
                                    0%
                                 | 
| 9998 | dk | 0 | 
                                    
                                    0%
                                 | 
| 9999 | missing | 0 | 
                                    
                                    0%
                                 | 
| Sysmiss | 14872 |