Year	% of total
1970	76.9375032055869
1971	76.75146642510178
1972	76.16484390727679
1973	76.12879911055185
1974	75.52238903287594
1975	75.10171937802895
1976	74.74160057517936
1977	74.84774792403789
1978	74.88909260185262
1979	74.56957633210092
1980	74.27147995073044
1981	73.80349430308287
1982	73.3496581874582
1983	73.39978800084192
1984	72.79964334226871
1985	72.68538045955455
1986	71.55439662492041
1987	69.93631210599027
1988	68.99709486978013
1989	68.09837489024503
1990	83.01258751960822
1991	82.78811041946531
1992	82.53548592750933
1993	82.31725417439704
1994	82.06839492553777
1995	81.25623311392772
1996	80.52395049399009
1997	79.72368096429705
1998	79.05731954476953
1999	78.31442796283939
2000	77.48917748917748
2001	77.07751807634101
2002	76.23984119174061
2003	75.98035120549365
2004	75.6842313526347
2005	75.66118828775173
2006	75.55499175440822
2007	75.56378114404802
2008	75.38780844031055