Year	% of total
1960	0
1961	0
1962	0
1963	0
1964	0
1965	0
1966	0
1967	0
1968	0
1969	0
1970	1.4466546112115732
1971	1.7531044558071585
1972	2.6035770885216207
1973	2.780016116035455
1974	3.069403714565005
1975	3.3132530120481922
1976	8.768585589020205
1977	13.47543352601156
1978	14.94603950315618
1979	12.196750500778991
1980	10.438983406847303
1981	13.090747725759929
1982	21.190188982710094
1983	23.3517044294754
1984	29.019384264538196
1985	31.533804238143286
1986	36.00832932884831
1987	32.85171102661597
1988	34.20444701126191
1989	35.04618937644342
1990	39.760076199013895
1991	42.63840336134454
1992	41.94723247232473
1993	41.60841070681723
1994	38.22560543657331
1995	35.9480311730927
1996	39.2584705882353
1997	38.528544212796554
1998	34.832476225310906
1999	38.355977011494254
2000	39.280406779661014
2001	38.41563997477932
2002	36.68161177960735
2003	26.416875
2004	24.152890173410405
2005	21.578143607705776
2006	22.102465753424656
2007	24.995783168613357
2008	22.69336339831248
2009	25.652608556832696
2010	27.434767105685832
2011	25.735453047775948
2012	27.470996563573884
2013	28.712321259842522
2014	31.652242843661526
2015	29.094495184840014
2016	30.918996151379087