Year	Overall average
2004	60.4166666666667
2005	59.7222220833333
2006	55.6790122222222
2007	53.580247037037
2008	54.0740737037037
2009	54.4444444444445
2010	58.2716051851852
2011	59.2592592592593
2012	57.2222223333333
2013	56.4444444444444
2014	56.8888888888889
2015	56.5555633333333
2016	58.0808090909091
2017	56.4646424242424
2018	58.8888909090909