Year	% of total
1960	66.73156485762959
1961	64.67589030735327
1962	62.422352623437845
1963	59.181231336729326
1964	55.14787872351723
1965	50.6675282175277
1966	47.403159717821985
1967	43.56024761454144
1968	40.394699208694824
1969	37.6496268756045
1970	33.277647844971604
1971	28.785872314780303
1972	24.482821748947337
1973	22.376808302218944
1974	23.225910740789725
1975	22.747710788014043
1976	23.685260264434756
1977	24.278012064271607
1978	22.629377523577553
1979	23.624759185596872
1980	24.780501255315134
1981	24.243939418377717
1982	25.961457756290812
1983	23.90559243351122
1984	24.171778031084333
1985	23.843543326533783
1986	20.277106829722893
1987	19.107661521424475
1988	19.760201769423265
1989	20.073030385521584
1990	21.02348880910978
1991	20.8158527936116
1992	18.9009748820051
1993	15.948769490458615
1994	16.027157454714352
1995	16.327039570795957
1996	16.85707821502337
1997	15.154428356629726
1998	16.862158560260244
1999	15.320237066666667
2000	14.892397920908799
2001	12.51038024730669
2002	13.591324460489803
2003	14.144865725506847
2004	13.515361820346605
2005	13.870893072842813
2006	13.187779332615715
2007	13.991609214405775
2008	13.517974093408894
2009	12.266343201116667
2010	12.996908662413063
2011	11.591515305969477
2012	12.696522760384147
2013	13.815928764518908
2014	11.341895051390667