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	96.67545454545456
1991	96.67545454545456
1992	73.34
1993	81.19785714285715
1994	80.674
1995	85.56333333333333
1996	88.008
1997	89.383125
1998	83.5261111111111
1999	89.63777777777779
2000	90.71
2001	83.81714285714285
2002	86.09478260869565
2003	86.09478260869565
2004	88.61916666666667
2005	90.00818181818182
2006	87.68913043478261
2007	86.5412
2008	86.5412
2009	31.955285714285715
2010	91.67500000000001
2011	88.85423076923077
2012	62.862857142857145
2013	97.25521739130436
2014	100.44391304347826
2015	97.78666666666666
2016	95.342