Year	% of total
1960	5.315818222997908
1961	6.71223273746933
1962	6.905018702526562
1963	5.834597875569044
1964	4.318368256347414
1965	3.170055975423585
1966	3.6006605723155225
1967	3.6214773368923563
1968	4.38690418248483
1969	4.757055571719523
1970	4.4972824236149895
1971	4.75331891767031
1972	5.435715912874341
1973	5.528524776996077
1974	5.6912875240169765
1975	6.597083553703843
1976	5.158435224451925
1977	4.562128771679734
1978	2.976408941166066
1979	3.6104445895312907
1980	2.722806908452127
1981	2.089758008925008
1982	1.9223034603616935
1983	1.669832305770266
1984	1.214307630798412
1985	0.920438821324521
1986	0.7904085996455642
1987	0.6471116400401655
1988	0.6186063674942086
1989	0.7369887047931525
1990	0.7255530334444714
1991	0.6762442096312764
1992	0.6923747475603844
1993	0.7443777759797638
1994	0.7638123613285488
1995	0.7817573661291407
1996	0.8095687013905256
1997	0.9780927191975647
1998	0.9807477733575678
1999	1.4774469195394802
2000	2.151409608657957
2001	2.7776249527770744
2002	3.3179199104094796
2003	3.449307573944264
2004	3.7011833799300167
2005	4.038619772062814
2006	3.8213518032003817
2007	3.900050021108198
2008	3.84738450286743
2009	3.8636573493912336
2010	4.210283810485836
2011	4.80880700966075
2012	3.895582114178269
2013	3.0281337499206558
2014	2.2914624025581785
2015	3.5127259562657276