| Value | Category | Cases | |
|---|---|---|---|
| 1 | Less than a month | 1 | 
                                    
                                    1.1%
                                 | 
| 2 | 1-5 months | 23 | 
                                    
                                    26.4%
                                 | 
| 3 | 6-12 months | 25 | 
                                    
                                    28.7%
                                 | 
| 4 | over 1 year | 36 | 
                                    
                                    41.4%
                                 | 
| 9 | 2 | 
                                    
                                    2.3%
                                 | |
| Sysmiss | 340 |