Year	% of total
1970	52.35047296033607
1971	53.59321603577437
1972	54.14185800873968
1973	54.54607985722527
1974	55.151807557447576
1975	54.8847400561808
1976	55.01558361136978
1977	55.36122799464882
1978	56.245530694028865
1979	56.575067454015624
1980	41.262163698885544
1981	41.23804786524983
1982	42.141197285757784
1983	44.561535003618815
1984	44.07457766746534
1985	44.76277453559142
1986	46.34222396711986
1987	46.93652887412824
1988	46.973221166892806
1989	46.26134836721336
1990	91.44385026737967
1991	90.9090909090909
1992	92.15686274509804
1993	92.08633093525181
1994	91.2
1995	90
1996	88.79310344827587
1997	88.69565217391305
1998	89.83050847457628
1999	90.51724137931035
2000	90.67796610169492
2001	88.03418803418803
2002	87.17948717948718
2003	89.83050847457628
2004	89.25619834710744
2005	89.07563025210085
2006	89.91596638655463
2007	89.43089430894308
2008	89.92248062015504