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	9.481950089192122
1991	8.62277101369296
1992	8.580337808575141
1993	9.762766253540496
1994	9.862717313464673
1995	10.338096353556649
1996	8.506191169475157
1997	11.433156007864
1998	13.335328573260934
1999	12.112530054566134
2000	12.459986281010632
2001	11.199420025239643
2002	12.079247548529118
2003	11.234969048691982
2004	12.302405498281786
2005	13.720211952055763
2006	13.329769656915152
2007	12.4881531171149
2008	13.778541171608637
2009	12.5060705712581
2010	13.97352306815083
2011	15.958966544672862
2012	16.618142051668062
2013	17.950517142175507
2014	18.90621787529004
2015	20.053355102992843