Year	% of total
1960	100
1961	100
1962	100
1963	100
1964	100
1965	100
1966	100
1967	100
1968	100
1969	100
1970	100
1971	100
1972	100
1973	100
1974	100
1975	100
1976	100
1977	100
1978	100
1979	100
1980	100
1981	100
1982	100
1983	100
1984	100
1985	100
1986	100
1987	100
1988	100
1989	100
1990	97.78666666666666
1991	91.67500000000001
1992	84.12529411764706
1993	79.45166666666667
1994	73.34
1995	71.5065
1996	68.10142857142858
1997	68.10142857142858
1998	65.0059090909091
1999	66.96260869565218
2000	64.1725
2001	63.07240000000001
2002	60.64653846153847
2003	59.75851851851852
2004	52.04774193548387
2005	47.455294117647064
2006	50.00454545454544
2007	52.847941176470584
2008	56.1509375
2009	54.44939393939394
2010	55.005
2011	52.38571428571428
2012	50.93055555555556
2013	49.83358974358975
2014	57.162058823529414
2015	61.51096774193549
2016	46.85611111111111