| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 18 | 
                                    
                                    4.5%
                                 | 
| 1 | One month or less | 19 | 
                                    
                                    4.7%
                                 | 
| 2 | 20 | 
                                    
                                    5%
                                 | |
| 3 | 47 | 
                                    
                                    11.7%
                                 | |
| 4 | 16 | 
                                    
                                    4%
                                 | |
| 5 | 8 | 
                                    
                                    2%
                                 | |
| 6 | 102 | 
                                    
                                    25.4%
                                 | |
| 7 | 7 | 
                                    
                                    1.7%
                                 | |
| 8 | 16 | 
                                    
                                    4%
                                 | |
| 9 | 26 | 
                                    
                                    6.5%
                                 | |
| 10 | 10 | 
                                    
                                    2.5%
                                 | |
| 11 | 2 | 
                                    
                                    0.5%
                                 | |
| 12 | 111 | 
                                    
                                    27.6%
                                 | |
| Sysmiss | 553 |