Year	% of total
1990	46.9794753197764
1995	40.7728225723283
2000	39.8099890254266
2005	42.339719867244
2010	47.4020333782689
2011	49.5226402814278
2012	41.8905143041118
2013	36.7468029093427
2014	31.755803548988
2015	36.801055064569
2016	32.0477507252554
2017	32.4287920886407