Year	% of total
1990	96.6187881082772
1995	94.7182550024606
2000	93.0196692607509
2005	91.4492332140372
2010	92.9361431199384
2011	96.0183314899819
2012	90.536803243066
2013	88.08693768515
2014	81.929200996728
2015	86.0304757740664
2016	79.0229898750824
2017	79.9706558342916