Year	% of total
1970	77.07323326350055
1971	76.64942425661587
1972	72.75750828866018
1973	74.01685096102126
1974	73.86947918289536
1975	74.79648462186292
1976	75.49684918267516
1977	74.42066872053698
1978	74.36700656809639
1979	74.11123597089657
1980	71.80096757922493
1981	71.74905334619207
1982	71.41615633342674
1983	69.56228399152086
1984	65.94172060809579
1985	63.81921502073386
1986	59.26647951164077
1987	63.60143663042497
1988	63.812892121967934
1989	66.47513563067814
1990	59.75473801560758
1991	61.852260198456456
1992	63.07007786429366
1993	64.34195725534309
1994	66.18303571428571
1995	68.38074398249454
1996	70.89627391742196
1997	72.73584905660377
1998	74.05405405405405
1999	75.73715248525696
2000	72.80453257790369
2001	68.58974358974359
2002	73.19034852546918
2003	73.43205574912892
2004	72.77486910994764
2005	72.8363324764353
2006	58.092679650772325
2007	48.61878453038674
2008	44.20387911592242