| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 | 
                                    
                                    2.5%
                                 | 
| 1 | One month or less | 34 | 
                                    
                                    42.5%
                                 | 
| 2 | 6 | 
                                    
                                    7.5%
                                 | |
| 3 | 14 | 
                                    
                                    17.5%
                                 | |
| 4 | 3 | 
                                    
                                    3.8%
                                 | |
| 5 | 2 | 
                                    
                                    2.5%
                                 | |
| 6 | 17 | 
                                    
                                    21.3%
                                 | |
| 12 | 2 | 
                                    
                                    2.5%
                                 | |
| Sysmiss | 944 |