Year	% of total
1990	57.1227022882603
1995	54.0588954447093
2000	53.2251936743738
2005	55.9331257940224
2010	57.918628819866
2011	51.0056375512696
2012	53.6008959292176
2013	51.7408904322409
2014	45.9592884589363
2015	49.9252091421228
2016	33.8190329837959
2017	34.4287685632217