Year	% of total
1970	80.33492864609923
1971	80.49010826913992
1972	81.3024042144688
1973	81.59888348163379
1974	81.79331921384954
1975	81.67691549770531
1976	81.50934055333325
1977	81.33086523779177
1978	81.08301394789997
1979	81.1597152464459
1980	78.24499421131544
1981	75.18553227086505
1982	74.95629037334173
1983	74.69555740634341
1984	73.98817350752368
1985	73.06782820182198
1986	74.47000623531105
1987	73.25019534993439
1988	73.63503639163326
1989	72.23615867785615
1990	76.47058823529412
1991	76.66666666666667
1992	76.22950819672131
1993	74.59016393442623
1994	73.50427350427351
1995	73.77049180327869
1996	73.55371900826447
1997	73.77049180327869
1998	68.21705426356588
1999	68.18181818181817
2000	67.66917293233082
2001	67.4074074074074
2002	66.66666666666666
2003	65.21739130434783
2004	65.49295774647888
2005	64.82758620689654
2006	65.33333333333333
2007	65.56291390728477
2008	66.2420382165605