| Value | Category | Cases | |
|---|---|---|---|
| 1 | Calendar | 70 | 
                                    
                                    86.4%
                                 | 
| 2 | Body temperature | 1 | 
                                    
                                    1.2%
                                 | 
| 3 | Cervical mucus | 0 | 
                                    
                                    0%
                                 | 
| 4 | Body temp. & mucus | 5 | 
                                    
                                    6.2%
                                 | 
| 5 | No specific system | 3 | 
                                    
                                    3.7%
                                 | 
| 6 | Other | 2 | 
                                    
                                    2.5%
                                 |