Year	% of total
1990	2.52583085137683
1995	2.21350973792575
2000	1.76802999859005
2005	1.56938134528474
2010	1.64235535273383
2011	1.74160879992735
2012	1.27065425667295
2013	0.977555328555724
2014	0.654287418229016
2015	1.37509887124587
2016	0.682059397708845
2017	0.793323998016993