Year	% of total
1990	78.2932589059526
1995	65.8265151830878
2000	56.7722083123116
2005	56.348447184715
2010	58.7581396873634
2011	55.1448294349181
2012	44.0741829214253
2013	37.4456420492127
2014	40.6969645014996
2015	19.707234548105
2016	19.4285481121429
2017	16.8809193035778