Year	% of total
1990	47.3121834317466
1995	48.441874481214
2000	48.5010617167919
2005	45.7205131505085
2010	50.0544750716081
2011	48.9481224811092
2012	47.5640369977717
2013	50.1668008120128
2014	50.4406145889279
2015	46.09474628462
2016	42.2322989711755
2017	42.4802648672831