Year	% of total
1970	64.05743652960803
1971	63.908918310019814
1972	63.709847790141005
1973	64.47735421840348
1974	61.6614778702659
1975	63.2197396496036
1976	63.28447863775458
1977	64.98783242747545
1978	63.05921131712594
1979	64.18773832959349
1980	66.13719239342514
1981	64.7149873870507
1982	65.85398576584439
1983	64.78667066473076
1984	64.43762702963784
1985	63.14530760582898
1986	63.20897229694129
1987	63.17213393870602
1988	62.28544163401705
1989	63.823654938607966
1990	89.8989898989899
1991	88.88888888888889
1992	89
1993	90.0990099009901
1994	90.19607843137256
1995	89.10891089108911
1996	81.35593220338984
1997	81.03448275862068
1998	80.35714285714286
1999	79.62962962962963
2000	76.92307692307693
2001	83.09859154929578
2002	83.11688311688312
2003	88.69565217391305
2004	89.68253968253968
2005	89.16666666666667
2006	92.52873563218391
2007	91.61676646706587
2008	88.42975206611571