| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 5 | 
                                    
                                    5.8%
                                 | 
| 1 | One month or less | 31 | 
                                    
                                    36%
                                 | 
| 2 | 14 | 
                                    
                                    16.3%
                                 | |
| 3 | 11 | 
                                    
                                    12.8%
                                 | |
| 4 | 3 | 
                                    
                                    3.5%
                                 | |
| 5 | 1 | 
                                    
                                    1.2%
                                 | |
| 6 | 7 | 
                                    
                                    8.1%
                                 | |
| 7 | 1 | 
                                    
                                    1.2%
                                 | |
| 8 | 1 | 
                                    
                                    1.2%
                                 | |
| 10 | 2 | 
                                    
                                    2.3%
                                 | |
| 11 | 1 | 
                                    
                                    1.2%
                                 | |
| 12 | 9 | 
                                    
                                    10.5%
                                 | |
| Sysmiss | 129 |