Year	Overall average
2004	76.4814816296296
2005	79.148074037037
2006	79.3703334444444
2007	80.7036294444444
2008	80.7036296666667
2009	80.2962223703704
2010	80.5554815925926
2011	81.3333332222222
2012	80.7407405185185
2013	81.0740740740741
2014	80.7814814814815
2015	81.1851922222222
2016	82.847228125
2017	79.4097229166667
2018	78.3680625