Year	% of total
1990	98.8563901924566
1995	96.9795453858417
2000	93.9935369811394
2005	93.2470296671503
2010	95.1460232965776
2011	92.7988749695715
2012	83.4711718066527
2013	78.4600477694059
2014	71.4641813335251
2015	66.9628488716498
2016	52.9161665405516
2017	52.455124416793