Year	% of total
1990	47.81409705004301
1991	48.0753840196205
1992	30.974863678680677
1993	27.993047439240016
1994	27.932605025957898
1995	28.088129063327717
1996	19.55074173971679
1997	13.401389262002533
1998	13.242806061638005
1999	12.079499170312264
2000	6.566798206965251
2001	5.809360411762359
2002	5.121711521016026
2003	4.0785668682164715
2004	4.854213393143223
2005	3.036077646070863
2006	4.894533337524756
2007	0.7791636557856043
2008	2.873202465190596
2009	17.88253884645773
2010	2.37569852414386
2011	1.2236024844720497
2012	2.5617714860872107
2013	0.568127717650046
2014	1.0911184684036275
2015	1.0621442403614811