Year	% of total
1990	73.36474084437667
1991	72.43062029376706
1992	70.63716120407538
1993	67.78213712364563
1994	66.99026497122999
1995	66.16688111433277
1996	65.02130645760585
1997	64.92954706920739
1998	64.72237447482216
1999	64.4451332376075
2000	65.01242462601208
2001	65.0377163803931
2002	64.83360454093592
2003	65.64199923080228
2004	64.15406879499727
2005	64.9326852203774
2006	65.50235661140415
2007	66.96720937916574
2008	68.42874746990368
2009	66.41754895451584
2010	65.99381924994275
2011	67.41458116680673
2012	67.29042291148005
2013	66.29616212123285
2014	67.19472418087264
2015	65.38535962889165