Year	% of total
1990	83.0161261578205
1995	82.8934475943947
2000	82.475367571687
2005	84.0336337202235
2010	83.2231246462317
2011	84.5374109467694
2012	83.8958857106319
2013	82.6068714318773
2014	77.1901215141301
2015	71.2037959529239
2016	66.8428959677298
2017	67.1430303184805