Year	% of total
1970	68.04360188872512
1971	68.75898939943785
1972	68.23952853552126
1973	68.2372280879371
1974	70.33753579523075
1975	71.47241086410826
1976	72.34094382443989
1977	71.44929441001119
1978	69.56418200060747
1979	69.88366171773337
1980	69.90615527815653
1981	67.97213471710687
1982	67.72602406834022
1983	68.87646020728101
1984	68.1382975816338
1985	67.88576797548113
1986	67.58611609291178
1987	70.97012548232928
1988	70.42826544354054
1989	71.56191536624247
1990	69.23076923076923
1991	66.37037037037037
1992	61.53846153846154
1993	59.333333333333336
1994	56.01023017902813
1995	58.55263157894737
1996	61.91744340878829
1997	64.88340192043896
1998	67.98307475317348
1999	65.76576576576578
2000	64.61538461538461
2001	65.7393850658858
2002	66.2873399715505
2003	65.32374100719424
2004	67.11409395973155
2005	65.79310344827586
2006	65.578231292517
2007	67.82608695652173
2008	68