Year	% of total
1990	47.3710047114834
1995	45.3130318011553
2000	47.6113160216546
2005	44.9449259282996
2010	48.0698031218117
2011	46.012410456669
2012	46.9674609667583
2013	46.8398957108466
2014	48.89545533192
2015	53.7436596688988
2016	48.5863159265427
2017	49.6261579731812