Year	% of total
1960	0
1961	0
1962	0
1963	0
1964	0
1965	0
1966	0.27926460321154295
1967	0.24615384615384617
1968	0.36771465342893916
1969	0.3497059291050707
1970	1.2965050732807215
1971	2.0893183598850875
1972	2.2316185106882784
1973	2.085790965368607
1974	4.31072966632821
1975	5.310200234177189
1976	6.721802316407359
1977	5.9804938313583484
1978	10.63391493298337
1979	12.026001981754195
1980	14.42559442196143
1981	15.134177529313636
1982	17.69958908891093
1983	18.602292998606753
1984	20.8692192073166
1985	23.92685409953804
1986	25.078676330345225
1987	26.333114075378923
1988	23.880583049850628
1989	23.040500954408866
1990	23.18152281169024
1991	23.693268407902494
1992	24.684320276535768
1993	27.272299560261853
1994	27.616489073505505
1995	29.130730923759046
1996	29.654576195677024
1997	30.628368211757838
1998	31.7327991429529
1999	29.64727518228969
2000	29.59758917444481
2001	29.85069890977914
2002	27.027541909111974
2003	22.20327850654036
2004	25.44655486502898
2005	26.984632957458395
2006	26.842760374138674
2007	22.87438388409868
2008	23.442079098672185
2009	26.184773238459748
2010	25.28191399781065
2011	9.471487621382492
2012	1.5084722022425971
2013	0.8780018215022202
2014	0
2015	0.9115531660462143