Year	% of total
1960	0
1961	0
1962	0
1963	0
1964	0
1965	0
1966	0
1967	0
1968	0
1969	0
1970	0
1971	0
1972	0
1973	0
1974	0
1975	0
1976	0
1977	0
1978	0
1979	0
1980	0
1981	0
1982	0
1983	0
1984	0
1985	0
1986	0
1987	0
1988	0
1989	0
1990	6.928433179723504
1991	6.89665137614679
1992	6.89665137614679
1993	6.9689592760181
1994	8.04951219512195
1995	8.952300469483568
1996	12.004080717488788
1997	9.473083333333333
1998	9.963169811320755
1999	9.026461538461538
2000	8.712375886524823
2001	8.787781065088756
2002	8.227894736842105
2003	6.757371007371008
2004	5.153217922606925
2005	6.011475409836066
2006	5.87957805907173
2007	5.165813492063492
2008	6.111666666666666
2009	6.001876247504991
2010	5.770776892430279
2011	5.909922330097087
2012	5.313408163265307
2013	4.978145315487572
2014	5.185025553662691
2015	28.343685847589423
2016	21.146526867627784