Year	% of total
1990	22.7634639983298
1995	25.5609997719804
2000	25.820929412588
2005	27.7860014821175
2010	20.316804790177
2011	25.3458989669758
2012	23.6925173746115
2013	17.3590426095332
2014	12.7421027826896
2015	2.16131273801549
2016	2.14232585286259
2017	2.12282654412876