Year	% of total
1990	17.4509762457726
1995	17.696401246996
2000	22.1571787079081
2005	35.5793250955143
2010	37.1388821973607
2011	29.3882828240639
2012	7.38148163731028
2013	3.25608627383083
2014	3.09956323907761
2015	3.10874890392641
2016	2.91009808930971
2017	2.89726536077518