| Value | Category | 
                                    
                    
                        | 1 | Native fluency (mother tongue) | 
                                    
                    
                        | 2 | Fluent | 
                                    
                    
                        | 3 | Very good | 
                                    
                    
                        | 4 | Good | 
                                    
                    
                        | 5 | Functional | 
                                    
                    
                        | 6 | Minimal | 
                                    
                    
                        | 7 | Not able to | 
                                    
                    
                        | 9 | Don't know | 
                                    
                    
                        | Sysmiss |  | 
                            
            Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.