Year	% of total
1990	87.99325353207703
1995	86.98660012650292
2000	87.54581339016133
2005	88.35144779144488
2010	89.06934171113605
2011	89.13172831625009
2012	88.78666237863565
2013	88.78389511220456
2014	86.5845527819006
2015	86.5826515892673
2016	86.26809754740088
2017	85.7211749971719