Year	% of total
1960	58.0896686159844
1961	57.22284434490482
1962	58.11688311688311
1963	54.98055638647921
1964	52.57903494176372
1965	53.11221193194056
1966	56.567046795123865
1967	58.85113572367185
1968	61.048135370461644
1969	59.11904419173744
1970	66.38846737481032
1971	65.9986816084377
1972	68.00232288037165
1973	68.49409448818898
1974	65.49559582869293
1975	60.588623714743896
1976	58.579729960690486
1977	59.4054771007256
1978	63.476205003050644
1979	61.810122962539324
1980	62.7379679144385
1981	59.10931174089068
1982	57.436185922227686
1983	52.43282498184458
1984	51.72568931165241
1985	49.261769333171976
1986	47.1937984496124
1987	47.44930383037726
1988	47.20888840947091
1989	48.77409787444389
1990	46.858266331658285
1991	49.17707201266156
1992	48.3445497569711
1993	47.437615571776156
1994	47.85543082904804
1995	46.41295871559633
1996	50.21078298695022
1997	50.37747015281757
1998	49.902007345346036
1999	49.42897826086957
2000	47.015707177641325
2001	47.5294213849498
2002	48.67695755693582
2003	48.55792955497905
2004	48.73419128693039
2005	49.456841589014225
2006	49.53909433962264
2007	45.38488160291439
2008	48.55734687780102
2009	49.42360460206882
2010	46.60163279287509
2011	43.57029213483146
2012	46.248429267074535
2013	43.47479442604856
2014	46.94603594536305
2015	50.230513159829435
2016	51.91945400149588