Year	% of total
1990	93.11130501364532
1995	92.58049959789678
2000	92.14626211969194
2005	92.08904548437667
2010	91.54080377158584
2011	92.7468173152214
2012	89.4261902411566
2013	87.81210490105693
2014	82.98465576997863
2015	84.58756579547286
2016	77.53163529517283
2017	77.63897365602219