Year	Overall average
2004	57.7777778787879
2005	63.6363636363636
2006	64.4444445454545
2007	65.0505051515152
2008	66.0606057575758
2009	64.0404036363636
2010	62.9797981818182
2011	63.7373739393939
2012	62.727273030303
2013	61.6161616161616
2014	61.7171717171717
2015	63.0303181818182
2016	61.4141545454545
2017	59.2929303030303
2018	59.2424333333333