Year	% of total
1990	73.6649620893929
1995	62.11734368729
2000	53.2980819891892
2005	52.9323691033183
2010	61.0920211019441
2011	54.947686336395
2012	41.4742930513191
2013	31.9947004181755
2014	25.5975417263026
2015	29.5988210243144
2016	18.9153990700737
2017	19.131780762019