Year	% of total
1990	92.5779428749005
1995	93.8457774275618
2000	93.2886714822975
2005	93.884101656357
2010	93.0063619609267
2011	94.4118395057473
2012	93.2753532125302
2013	87.6255113188696
2014	79.6429571390786
2015	72.0199233663338
2016	58.364298755948
2017	57.6793861113927