Year	% of total
1970	88.93345524409783
1971	88.58997027357813
1972	88.71356354492256
1973	88.14062230972763
1974	84.30086368246629
1975	85.08455491991343
1976	85.40302751680872
1977	86.91178393214642
1978	85.60395198001544
1979	85.66300786411331
1980	87.05816068425882
1981	85.3586274177608
1982	86.4822617498947
1983	85.78780902101917
1984	83.88329512957645
1985	82.90861822999987
1986	83.10006345443864
1987	83.67311838690622
1988	83.47594021663588
1989	84.56490135078243
1990	87.77533039647577
1991	91.46067415730337
1992	91.52298850574712
1993	91.65517241379311
1994	91.6776750330251
1995	91.85606060606061
1996	92.32091690544412
1997	92.37618252643294
1998	92.35325794291869
1999	92.56825075834176
2000	92.93401965372017
2001	85.31177829099306
2002	80.33980582524272
2003	76.30434782608695
2004	72.87128712871286
2005	70.30921645151606
2006	72.01304476726949
2007	74.04953917050692
2008	75.75671852899576