Year	% of total
1970	99.1523202163329
1971	99.099454164904
1972	99.00493754737373
1973	98.7677179097955
1974	98.31439186618715
1975	97.77692719972687
1976	97.41340270808612
1977	96.90569129111427
1978	96.98291970118287
1979	96.8469742392843
1980	95.22016268591817
1981	93.26918341979771
1982	91.33223857907825
1983	92.12825791019098
1984	92.31912745730841
1985	91.75859053291117
1986	91.53356654025909
1987	90.86368871508354
1988	91.66529609591929
1989	92.33076727176763
1990	59.51417004048582
1991	63.39622641509434
1992	65.625
1993	67.19745222929936
1994	68.43657817109144
1995	69.5054945054945
1996	69.10569105691057
1997	68.63270777479893
1998	68.16976127320955
1999	67.80104712041884
2000	67.18346253229974
2001	68.34170854271356
2002	68.02884615384616
2003	68.28703703703704
2004	68.76404494382022
2005	69.1304347826087
2006	67.74891774891775
2007	66.23655913978494
2008	64.74358974358975