Grade
21-2 & better
                                            
                                            53.5%
                                        21-3
                                            
                                            26.3%
                                        31-3
                                            
                                            16.1%
                                        31-4
                                            
                                            0.9%
                                        41-4
                                            
                                            2.7%
                                        
