| Value | Category | Cases | |
|---|---|---|---|
| 1 | 1 year or less | 220 | 
                                                                 
                                    
                                    9.9%
                                 
                                                             | 
                                                        
                    
| 2 | Between 1 and 2 years | 146 | 
                                                                 
                                    
                                    6.6%
                                 
                                                             | 
                                                        
                    
| 3 | More than 2 years | 407 | 
                                                                 
                                    
                                    18.4%
                                 
                                                             | 
                                                        
                    
| 4 | Never | 1430 | 
                                                                 
                                    
                                    64.6%
                                 
                                                             | 
                                                        
                    
| 77 | Don't know | 12 | 
                                                                 
                                    
                                    0.5%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 1837 |