Year	% of total
1970	68.5114003384206
1971	72.4862070429111
1972	70.58775093467705
1973	72.04667945239935
1974	70.92179374082806
1975	70.44740422306609
1976	69.44533855040841
1977	71.60393578476142
1978	70.8732349567038
1979	69.76902463376814
1980	69.01396305387524
1981	68.97256249683399
1982	68.60972017986268
1983	69.32544112659484
1984	71.75802195981194
1985	73.21150115924064
1986	73.47296776874032
1987	72.69603355308284
1988	74.70404136215971
1989	74.1476471257538
1990	94.10058027079303
1991	94.0453686200378
1992	93.89312977099237
1993	93.56725146198829
1994	93.51763584366063
1995	93.50893697083725
1996	93.21705426356588
1997	93.15992292870907
1998	93.14938154138915
1999	92.78152069297401
2000	93.1716082659479
2001	93.16823228010249
2002	92.8388746803069
2003	92.86871961102106
2004	92.53246753246754
2005	92.5233644859813
2006	92.04455051710421
2007	91.96633511859218
2008	92.04959883296864