Year	% of total
1970	71.15411236997794
1971	68.19771010512797
1972	69.73892285135224
1973	71.12443972350304
1974	66.93996358786698
1975	66.98900210402522
1976	67.0526889562489
1977	70.72966041491911
1978	71.37377681369004
1979	70.81353635281248
1980	71.98300768554276
1981	71.580733322328
1982	71.74267361398284
1983	72.79832435667265
1984	71.20546205426528
1985	70.7605877841113
1986	71.77140817232764
1987	72.47920787213916
1988	71.56041871395001
1989	70.47317573260541
1990	89.1025641025641
1991	89.30817610062893
1992	89.82035928143712
1993	89.88095238095238
1994	90.3409090909091
1995	90.55555555555556
1996	89.83050847457628
1997	90.55555555555556
1998	89.28571428571429
1999	88.75
2000	89.41176470588236
2001	89.77272727272727
2002	90.21739130434783
2003	89.47368421052632
2004	90.29126213592234
2005	90.29126213592234
2006	90.04975124378109
2007	90.990990990991
2008	90.27777777777779