Year	% of total
1970	65.01104758213006
1971	68.10183841912394
1972	66.73542691216706
1973	69.01099264945034
1974	68.84058082571052
1975	68.44400401300045
1976	68.26681840215045
1977	71.4512084912483
1978	69.3608525679283
1979	69.05820262357348
1980	68.37751715213619
1981	70.54078119959523
1982	70.48915153458276
1983	70.70285089229647
1984	74.00251119996148
1985	74.19685698204684
1986	73.1495451305204
1987	71.8378297364222
1988	74.14497955456905
1989	74.50572727587708
1990	42.76729559748428
1991	47.7892756349953
1992	57.76053215077606
1993	73.08192457737321
1994	94.51612903225806
1995	94.9618320610687
1996	94.75409836065573
1997	94.94290375203916
1998	95.16908212560386
1999	95.5108359133127
2000	88.15165876777252
2001	89.74008207934337
2002	89.59778085991678
2003	90.31847133757962
2004	89.31082981715893
2005	89.96036988110964
2006	89.82826948480846
2007	90.89848308051342
2008	90.1015228426396