Year	% of total
1960	79.7506448839209
1961	79.37136819862653
1962	84.43896424167694
1963	75.65882996172772
1964	79.03877221324717
1965	80.37798777098388
1966	81.82999740057187
1967	85.38963792080048
1968	84.45520581113801
1969	78.01697998787144
1970	81.40599299148967
1971	84.74609122625662
1972	81.04808947936183
1973	77.25433058118828
1974	75.40365413214361
1975	82.05115736238085
1976	69.57028337061895
1977	66.84073107049609
1978	72.93916486681066
1979	84.64812969839687
1980	83.76703841387855
1981	83.23677259947175
1982	72.03444132959551
1983	76.2390065300268
1984	73.27890958125296
1985	71.08281633241957
1986	76.2458006718925
1987	75.81470416537893
1988	77.49079959852794
1989	70.67733911601505
1990	71.85185185185186
1991	68.75300336376742
1992	64.11807624490788
1993	68.53683442742525
1994	74.12699779059425
1995	76.34629249625645
1996	71.77912428371673
1997	62.66943329111536
1998	67.31096458577049
1999	60.599730280032794
2000	62.254439829795906
2001	54.783685434145355
2002	61.21243446799084
2003	57.92481055496971
2004	63.61406950672646
2005	54.28458387637312
2006	54.05944681436632
2007	54.02600964505291
2008	50.958929100818686
2009	55.72917865279727
2010	55.08863352930696
2011	56.464267248162216
2012	51.73730345201518
2013	53.25182582971249
2014	55.894724744282264
2015	55.5027711797308