Year	% of total
1990	96.5541939709896
1995	96.1620687074986
2000	96.9535375804697
2005	94.8417847725358
2010	92.4845959460551
2011	92.0156118366716
2012	92.9120532120943
2013	93.2738595743476
2014	91.8410357207503
2015	93.2268870961593
2016	89.6348215695102
2017	89.5883458229235