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	0.014692918013517485
1979	0.027135814752837953
1980	0.04109844946758827
1981	0.055659565855386325
1982	0.08008092388097446
1983	0.27052617340727714
1984	0.2911079745942131
1985	0.29851770518803183
1986	0.57499269077088
1987	0.7969073213740716
1988	1.3252582828642678
1989	2.4157327868137615
1990	3.0675082749595872
1991	2.8239157203447807
1992	4.307371982562301
1993	4.647671748984518
1994	4.214106165902706
1995	4.954023613907177
1996	3.8445746705983352
1997	6.56662529617511
1998	9.481185999562182
1999	11.17163412127441
2000	15.371813718691927
2001	15.420498820535927
2002	17.199073484867768
2003	17.444680206123067
2004	23.48897022455238
2005	27.00711802681675
2006	20.12233890947359
2007	26.139485196866413
2008	27.50163862792222
2009	27.606299645438803
2010	31.928361895939478
2011	40.20551250390304
2012	48.27204325592
2013	45.92291972483666
2014	55.85384041759881
2015	65.44374201126196