| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 | 
                                    
                                    0.8%
                                 | 
| 1 | One month or less | 38 | 
                                    
                                    31.1%
                                 | 
| 2 | 16 | 
                                    
                                    13.1%
                                 | |
| 3 | 39 | 
                                    
                                    32%
                                 | |
| 4 | 5 | 
                                    
                                    4.1%
                                 | |
| 5 | 3 | 
                                    
                                    2.5%
                                 | |
| 6 | 8 | 
                                    
                                    6.6%
                                 | |
| 7 | 3 | 
                                    
                                    2.5%
                                 | |
| 8 | 2 | 
                                    
                                    1.6%
                                 | |
| 9 | 1 | 
                                    
                                    0.8%
                                 | |
| 12 | 6 | 
                                    
                                    4.9%
                                 | |
| Sysmiss | 241 |