Year	% of total
1990	15.7071481072095
1995	15.3586095995048
2000	16.6453579689054
2005	13.5724766970722
2010	11.6653966511462
2011	16.5031731760765
2012	22.6361662747326
2013	26.2572062742919
2014	17.376009983868
2015	15.1986322026472
2016	19.3712472268431
2017	19.2886889322296