| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 | 
                                    
                                    7.1%
                                 | 
| 1993 | 1 | 
                                    
                                    7.1%
                                 | |
| 1996 | 1 | 
                                    
                                    7.1%
                                 | |
| 2003 | 1 | 
                                    
                                    7.1%
                                 | |
| 2006 | 1 | 
                                    
                                    7.1%
                                 | |
| 2007 | 1 | 
                                    
                                    7.1%
                                 | |
| 2009 | 1 | 
                                    
                                    7.1%
                                 | |
| 2011 | 1 | 
                                    
                                    7.1%
                                 | |
| 2021 | 2 | 
                                    
                                    14.3%
                                 | |
| 2022 | 3 | 
                                    
                                    21.4%
                                 | |
| 2023 | 1 | 
                                    
                                    7.1%
                                 | |
| Sysmiss | 136 |