Year	% of total
1960	35.255447032306535
1961	29.35251798561151
1962	25.899499013207834
1963	25.475620511528284
1964	18.3830230438745
1965	14.585848828785316
1966	11.316585252384275
1967	8.445945945945946
1968	6.697201017811705
1969	6.083357397247088
1970	5.35080535080535
1971	3.488372093023256
1972	3.0292687089342096
1973	2.671211160431198
1974	2.51944837340877
1975	1.9789908084787096
1976	1.8206521739130435
1977	2.3027490182077828
1978	2.0932858507773817
1979	2.232635060639471
1980	3.175033921302578
1981	4.935359063886005
1982	5.105616177795575
1983	4.877825569689759
1984	5.110923897781522
1985	5.027161403185711
1986	4.066238945725681
1987	3.999271203425344
1988	3.4047919293820934
1989	3.4934497816593884
1990	3.131294714978075
1991	2.5212130501423258
1992	1.7733194748358863
1993	1.5444441887226699
1994	1.6014604367222351
1995	1.6629811233885818
1996	1.2414973869575097
1997	0.9864444444444445
1998	0.7872655367231638
1999	0.8070199865259374
2000	1.174513841226264
2001	1.209882639503986
2002	1.1446224466375947
2003	1.1367372881355933
2004	1.0771002650176678
2005	1.20767066521265
2006	1.2094327176781001
2007	1.490718879191548
2008	1.3131383451957295
2009	1.251163269979391
2010	1.216655607166556
2011	1.246370478271425
2012	1.096559924652696
2013	1.0963891444342226
2014	1.3752403725144726
2015	1.2871611580835254
2016	1.1201893461247159