Year	% of total
1970	70.99417506216012
1971	71.77824075243126
1972	72.0105471342265
1973	72.01699066936504
1974	72.22251567193128
1975	72.56906809648189
1976	72.44070664933992
1977	72.3829935836324
1978	72.82727063382578
1979	72.94525911398561
1980	72.78861134635942
1981	72.53282716224761
1982	72.57083445381394
1983	72.5696620402343
1984	72.73466436685626
1985	72.7532702673491
1986	72.70201980515994
1987	72.79068281452746
1988	66.90582483764416
1989	63.002319931167165
1990	72.7047146401985
1991	71.39303482587064
1992	76.70329670329672
1993	74.80916030534351
1994	65.6140350877193
1995	61.77606177606177
1996	60.3921568627451
1997	59.42622950819673
1998	58.119658119658126
1999	56.05381165919282
2000	51.65876777251185
2001	50.23474178403756
2002	51.1520737327189
2003	53.333333333333336
2004	51.9607843137255
2005	50.970873786407765
2006	52.19512195121951
2007	51.21951219512195
2008	52.17391304347826