Year	% of total
1990	66.94504593626864
1991	64.6421226248514
1992	56.159608619757186
1993	56.22926936209768
1994	58.53678339616971
1995	58.11742310230602
1996	59.62447530594617
1997	58.04978938800373
1998	53.85336158857543
1999	53.461441020089474
2000	51.64955272016315
2001	50.36879378242015
2002	52.961780615264786
2003	55.445640413776204
2004	56.435708394621706
2005	57.99839318023757
2006	59.02124335184032
2007	56.03092518231377
2008	61.46818971768501
2009	57.6421439788985
2010	61.36979605442613
2011	62.80765106994777
2012	62.83858013788137
2013	61.004892486414576
2014	60.690681595686584
2015	60.08730385718988
2016	57.84784849569535