Year	Overall average
2004	57.2327042767296
2005	58.8679244654088
2006	59.2386830246913
2007	59.6502056790123
2008	59.1563785185185
2009	59.6090535802469
2010	60.9259260493827
2011	60.9259258024691
2012	60.6378599382716
2013	60.0694444444445
2014	60.8630952380952
2015	61.9642988095238
2016	61.5873130952381
2017	61.3690547619048
2018	63.6706428571429