Year	% of total
1960	89.8076548458952
1961	90.54418807139749
1962	91.61804022699623
1963	92.46251356747558
1964	93.16442074885666
1965	91.61247047157981
1966	90.90404849362983
1967	90.986001482709
1968	91.39907292434489
1969	91.96207914575662
1970	91.39653659184314
1971	93.14314176666697
1972	92.61653574495274
1973	91.91910287643715
1974	91.01937459513574
1975	88.45636709487454
1976	88.86771723422784
1977	85.38327391193114
1978	85.2951287351498
1979	84.08120229354562
1980	82.8247630484196
1981	80.66712703934049
1982	78.8218128683704
1983	78.81231517795348
1984	74.6968104237997
1985	69.15667742431228
1986	70.5894640417161
1987	68.69531940723928
1988	66.83988017013063
1989	66.85432465549688
1990	68.01752944398794
1991	68.63552720472691
1992	65.76380248542175
1993	65.92699914064848
1994	65.86247274873621
1995	65.41269561235254
1996	65.12672260850458
1997	63.685765431715794
1998	65.0194161575017
1999	63.17765973812087
2000	63.154602464036294
2001	62.698707306929535
2002	62.79293552411359
2003	64.37857333379722
2004	62.68169954426816
2005	62.31682364404028
2006	61.027101521655304
2007	62.79236755183749
2008	60.75207289006589
2009	59.738866307549934
2010	59.457246685594725
2011	60.40087084258302
2012	59.681137950163375
2013	59.23832244507816
2014	56.73234309529246
2015	55.063053168103814