Year	% of total
1970	85.29700994306059
1971	85.32619720165692
1972	85.81862184446209
1973	86.22051255454876
1974	85.05743768260085
1975	84.28954756910507
1976	85.3392987845865
1977	85.349831683145
1978	84.22222966298906
1979	84.49384179861462
1980	84.46410656256134
1981	83.67493963495374
1982	83.70709829457104
1983	84.77117938415145
1984	84.51834536608331
1985	83.69765279089262
1986	82.65483280984131
1987	82.71536228341554
1988	82.31884881595637
1989	83.59430175345277
1990	93.07479224376732
1991	93.04812834224599
1992	93.31619537275064
1993	93.30024813895783
1994	93.47826086956522
1995	93.36492890995261
1996	93.70786516853933
1997	93.7759336099585
1998	93.52051835853132
1999	93.02325581395348
2000	92.09876543209876
2001	93.56060606060606
2002	92.25941422594143
2003	91.50743099787687
2004	91.26016260162602
2005	90.42553191489363
2006	90
2007	88.96247240618102
2008	89.43089430894308