Year	% of total
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	1.3280281107895824
1989	10.090634441087614
1990	12.738964198818215
1991	13.07999397408858
1992	11.906954534602136
1993	9.171248452747632
1994	8.52685421994885
1995	7.588755444107166
1996	6.661350552357242
1997	5.493841024134893
1998	5.7238391724728634
1999	6.9903269817423705
2000	11.105335354848025
2001	12.485228743458443
2002	15.167881048903014
2003	18.871146567434273
2004	23.355694910310632
2005	24.180808728363555
2006	23.066904152287655
2007	27.69801878666065
2008	26.76864244741874
2009	28.714774617897813
2010	34.32997291362813
2011	40.98472249081416
2012	41.51479747881025
2013	38.57807846878885
2014	37.85676989740217
2015	42.28132930996583