Year	% of total
1970	81.01379421731751
1971	81.80808016877637
1972	81.36459474888889
1973	81.43410417958957
1974	81.14903205800269
1975	79.84599683544303
1976	79.11743601953259
1977	79.32370125440039
1978	79.17475460013208
1979	78.85127034459167
1980	78.80058616995954
1981	78.52400587733594
1982	78.67756703401055
1983	79.4883311864434
1984	79.74444758683809
1985	79.91841053653891
1986	79.68580506858302
1987	79.72915956114271
1988	79.06123742365907
1989	78.44498414540138
1990	87.5
1991	86.74698795180723
1992	86.66666666666667
1993	84.61538461538461
1994	84.48275862068965
1995	84.21052631578947
1996	85.96491228070175
1997	85.71428571428571
1998	87.03703703703704
1999	86.53846153846155
2000	86.79245283018868
2001	87.03703703703704
2002	87.3015873015873
2003	88.52459016393442
2004	89.39393939393939
2005	87.5
2006	91.57894736842105
2007	89.87341772151899
2008	87.17948717948718