Year	% of total
1960	94.62158342052608
1961	93.97716023193324
1962	93.36332577884518
1963	93.26608938370285
1964	92.47639446137138
1965	91.32575869945711
1966	90.67715438423359
1967	89.80864695150409
1968	88.57556517812077
1969	87.98826173826174
1970	85.96034785960349
1971	85.57063086054107
1972	85.21655052845664
1973	83.71971242486063
1974	83.36363828572637
1975	82.61892673019841
1976	82.0608722821592
1977	81.65556712669228
1978	81.50021642633442
1979	81.16236284681936
1980	82.05555248596981
1981	82.11580594679185
1982	82.90225642272752
1983	83.11583444036363
1984	84.45623880193367
1985	85.0713005148111
1986	84.5618150200186
1987	84.89397413772724
1988	84.729359721754
1989	84.05527481655821
1990	87.8176451944492
1991	85.9231191877826
1992	85.78902554096165
1993	84.57912795767687
1994	79.03342899190582
1995	80.67292147058825
1996	78.96042159180456
1997	79.13050401880277
1998	77.6449043685814
1999	76.44469027121497
2000	74.10884109431537
2001	74.58897820163487
2002	74.50923280423281
2003	73.12320725562647
2004	70.95988834404612
2005	70.07273768043804
2006	70.99916297876405
2007	68.88160576953761
2008	69.22366405033732
2009	67.2978261454619
2010	68.05935169248423
2011	68.22303615699154
2012	64.94343431679577
2013	69.2468447692153
2014	66.98236088752012
2015	64.98474589171424
2016	63.85502935877761