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	96.84641025641027
1991	96.25875
1992	99.27731707317072
1993	98.38292682926829
1994	96.91357142857142
1995	95.84204545454546
1996	96.97177777777777
1997	98.05239130434784
1998	98.30680851063829
1999	97.2877551020408
2000	95.62960784313725
2001	96.61134615384616
2002	96.17226415094339
2003	97.9475
2004	97.15168831168832
2005	95.800375
2006	96.59414634146341
2007	97.09215909090908
2008	97.658
2009	97.15659793814433
2010	96.83728155339806
2011	100.17170731707317
2012	95.58921348314607
2013	95.26228260869566
2014	95.96617021276596
2015	92.9981443298969
2016	89.87745098039215