Year	% of total
1960	44.199071887423855
1961	44.15911346707507
1962	49.0496657421752
1963	51.626279505991334
1964	53.97489236859649
1965	56.08172970749894
1966	59.44922183786405
1967	60.624610711811265
1968	62.18319546684407
1969	64.16108790981964
1970	65.65402953079007
1971	82.7064146844077
1972	82.69014931744731
1973	83.02227912429969
1974	82.70940989565844
1975	82.11514489741744
1976	81.21431991359243
1977	81.82799000212701
1978	81.70285060311541
1979	80.64123965903752
1980	81.13290466134885
1981	79.29985120709448
1982	79.25702624098882
1983	79.56749543235198
1984	79.729790233551
1985	80.5923572738263
1986	81.5062033510538
1987	81.87182945170215
1988	79.91251879016777
1989	81.67754405983361
1990	92.90616317536323
1991	92.84252130417885
1992	92.12116393824236
1993	91.54887915819789
1994	91.32444129851484
1995	90.97268678307488
1996	90.42953183958825
1997	90.24307213317464
1998	90.25112686944597
1999	89.87290857899717
2000	89.69468424464664
2001	89.5946797258953
2002	89.50753291704146
2003	89.82900442479486
2004	89.65046016344996
2005	89.58141615634965
2006	89.61306168106917
2007	89.76203150239319
2008	90.03081737006026
2009	89.24507144834466
2010	89.40607876314016
2011	89.88207808544017
2012	89.74865726359752
2013	88.70333855944926
2014	89.87366521852701
2015	86.84318766070803