Year	% of total
1990	96.4546780032653
1995	96.696984604166
2000	97.1112587663611
2005	97.342018810621
2010	97.5554477431689
2011	97.5981644659335
2012	97.6412101797965
2013	97.6842895926093
2014	96.6759626389325
2015	97.7691467083986
2016	91.6379574913542
2017	94.1326775498377