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	-0.7295276308590188
1978	7.044198895027624
1979	8.987181293139878
1980	8.62750442960338
1981	11.658393788977984
1982	4.517820956013828
1983	12.273932963588134
1984	19.638739431206766
1985	20.063025210084035
1986	26.001291989664082
1987	24.400405359756785
1988	22.939754180938948
1989	28.669679701316564
1990	25.7167553338875
1991	27.854672869147656
1992	30.4373102310231
1993	28.869896238651105
1994	25.580158730158725
1995	24.19887436649773
1996	24.784824873096444
1997	26.188821263482282
1998	25.558714285714284
1999	20.84004466631634
2000	23.8396388261851
2001	24.34045377745595
2002	23.944837155963302
2003	23.875250677506774
2004	28.30256539898879
2005	22.488644412782417
2006	24.429335628924452
2007	26.173618492114926
2008	24.451416359044103
2009	20.893926779409032
2010	23.079737899702952
2011	26.743561103810777
2012	20.49453346080306
2013	24.153253318785232
2014	18.617549413735343
2015	23.667951337295694
2016	18.678915592028137