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	56.18210452776711
1972	56.64035821403452
1973	57.82240217675722
1974	58.87666793032958
1975	59.25905648055704
1976	60.43458684612917
1977	61.63772528619459
1978	62.11382609607491
1979	63.45809749622697
1980	64.773308754404
1981	66.24525247468837
1982	67.28231449002314
1983	67.1787910311207
1984	67.37356051252719
1985	68.08271812182736
1986	68.40550484485658
1987	69.20655178324701
1988	69.73197145138603
1989	70.29494462958596
1990	71.19373646754657
1991	71.31681632060827
1992	71.82451964835627
1993	72.40467574018346
1994	73.03720213643994
1995	73.8844625521144
1996	74.19710848779731
1997	74.48672398056819
1998	74.79100823680497
1999	75.23841770002927
2000	75.21748327798758
2001	75.58610673382844
2002	75.85255509612962
2003	76.18531260022357
2004	76.82659726754952
2005	77.17107389240073
2006	77.6697272386685
2007	78.22968464277041
2008	78.82466983282586
2009	79.21596225323468
2010	79.28369723469687
2011	78.87501664601541
2012	79.3794253154833
2013	79.00253666660687
2014	79.50189014419063
2015	89.53660154092321