Year	Overall average
2004	58.444444
2005	61.5555556666667
2006	60.7070706060606
2007	62.0202021212121
2008	62.6262624242424
2009	62.6262627272727
2010	63.333333030303
2011	62.8282821212121
2012	61.6161609090909
2013	62.020202020202
2014	64.2424242424242
2015	63.4343484848485
2016	65.1515090909091
2017	64.1414121212121
2018	67.8787878787879