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	0.41487940369875537
1983	0.28388459761008783
1984	0.3020759688926023
1985	0.2722981967808302
1986	0.34728682170542635
1987	0.3697498411231151
1988	0.3883285691170919
1989	0.4152249134948097
1990	0.41703517587939704
1991	0.41109865470852014
1992	0.3705461754924533
1993	0.27236009732360095
1994	0.13797817634516493
1995	0.11951834862385322
1996	0.13735741904301596
1997	0.468444364851958
1998	1.9065201423160796
1999	3.192891304347826
2000	4.134400804573364
2001	3.9892526653555533
2002	4.270574534161491
2003	4.632231091598483
2004	5.112132198297446
2005	5.28738597351643
2006	6.2488301886792454
2007	7.386029143897997
2008	7.997938452345384
2009	7.183820983744986
2010	8.457798584151632
2011	10.76029213483146
2012	10.471256086902235
2013	10.224899282560704
2014	8.182867002156723
2015	9.015180120570504
2016	11.958204936424831