Year	% of total
1970	57.907481571635245
1971	57.71459513209338
1972	54.988814322497724
1973	53.9628942023596
1974	53.74174993141345
1975	52.254779859503664
1976	55.0874339127671
1977	56.04599947625698
1978	53.08786434075705
1979	52.094464680046606
1980	51.410525788120744
1981	52.37782249742003
1982	55.04595943983095
1983	51.29702991022588
1984	50.393033968675596
1985	52.36609568910562
1986	52.502624618766994
1987	52.251226421432776
1988	52.23228164279635
1989	51.220086937316786
1990	64.34108527131784
1991	64.79591836734694
1992	66.02451838879159
1993	65.23235800344234
1994	64.54849498327759
1995	64.09395973154362
1996	63.31658291457286
1997	63.5
1998	63.869863013698634
1999	64.38356164383562
2000	64.79591836734694
2001	64.82758620689654
2002	64.88294314381271
2003	63.21070234113713
2004	62.908496732026144
2005	63.03317535545023
2006	63.04347826086957
2007	63.85737439222042
2008	64.71494607087827