Year	% of total
1971	100
1972	100
1973	100
1974	100
1975	100
1976	100
1977	100
1978	100
1979	100
1980	100
1981	100
1982	94.63986599664992
1983	82.37037037037037
1984	79.14285714285715
1985	56.37755102040817
1986	70.94117647058825
1987	63.13559322033898
1988	57.57281553398058
1989	43.81818181818182
1990	44.09090909090909
1991	58.42142353770261
1992	62.41610738255034
1993	60
1994	76.70343932511356
1995	94.48529411764706
1996	100
1997	100
1998	100
1999	100
2000	100
2001	100
2002	100
2003	100
2004	100
2005	100
2006	100
2007	100
2008	100
2009	100
2010	99.9526963103122
2011	99.54107388710418
2012	98.8666085440279
2013	98.4451354953354
2014	96.65924276169265
2015	92.32540291634689