Year	% of total
1960	53.36244541484716
1961	51.56308851224105
1962	42.43968739381583
1963	45.03152206544581
1964	49.20953575909661
1965	47.65303915206576
1966	40.95744680851064
1967	35.14211886304909
1968	36.43330302636706
1969	36.749036499659944
1970	38.319755600814666
1971	43.18457014357377
1972	37.48952061580672
1973	35.45252075318891
1974	38.069241011984026
1975	46.38957816377171
1976	55.5287787928039
1977	58.03002370292336
1978	48.3895486935867
1979	46.945977739571084
1980	44.84615724186642
1981	52.87906638738084
1982	54.344276383636995
1983	61.89384147104199
1984	60.72810836961781
1985	64.07714491708724
1986	66.8823780401081
1987	68.82270823638902
1988	73.53597491104276
1989	73.60128617363344
1990	72.36808051761324
1991	66.31228492292198
1992	71.48959032907992
1993	72.88197813147337
1994	73.2473192838216
1995	69.48594396958764
1996	69.08113461130367
1997	70.74979210939667
1998	70.25119099177132
1999	65.5552181394878
2000	64.22648572765559
2001	66.75521893134373
2002	64.07637408471591
2003	60.737414731024955
2004	60.156768061483
2005	59.80951419388494
2006	53.613386729590054
2007	55.29492433544354
2008	53.02009155645982
2009	55.95966870723803
2010	53.68417382815905
2011	52.49611302643142
2012	51.20699017623538
2013	46.23384809328711
2014	51.14117156307729
2015	42.65948824823434