Year	% of total
1970	83.2989188030789
1971	83.24952529093963
1972	82.91557207915884
1973	74.12897463969253
1974	73.79621485953255
1975	74.34596933959668
1976	75.1315223290146
1977	76.24760346241656
1978	77.15470474839863
1979	77.09416110434316
1980	77.02341079218684
1981	76.58196442047691
1982	76.53732096600892
1983	76.26234318110593
1984	66.04671537199468
1985	60.99964679034039
1986	62.06014274374224
1987	60.31212026421584
1988	60.43819224594385
1989	60.45868143490579
1990	70.2433628318584
1991	70.06369426751591
1992	69.6938775510204
1993	69.62025316455697
1994	69.5692883895131
1995	69.3969396939694
1996	69.3103448275862
1997	69.23076923076923
1998	69.10828025477707
1999	69.03669724770643
2000	69.25329428989751
2001	69.33895921237693
2002	69.37669376693766
2003	69.57654723127035
2004	69.71214017521903
2005	69.82498491249245
2006	69.58792803250145
2007	69.60621186910704
2008	69.6068012752391