Year	Overall average
2004	74.327485380117
2005	77.8946197076023
2006	78.0116373684211
2007	79.0642107017544
2008	80.3507601754386
2009	80.467719005848
2010	80.4677195321637
2011	80.9356728070176
2012	80.9356722222222
2013	78.1111111111111
2014	78.0611111111111
2015	77.277785
2016	77.7777833333333
2017	78.888895
2018	77.8611183333333