Year	% of total
1970	39.349679112585044
1971	40.162535764696905
1972	40.56119821335607
1973	38.97226330066503
1974	39.937820737239804
1975	41.08066640287286
1976	41.67373641094338
1977	42.86640635246593
1978	42.91041231041085
1979	42.425755855801015
1980	45.041482555308335
1981	44.742638694459885
1982	46.982401701241216
1983	45.94036592316007
1984	45.32885722292068
1985	46.31686569989776
1986	48.05016360551282
1987	48.58036807876791
1988	49.4872929153343
1989	47.35749309721031
1990	52.11845102505694
1991	50.86875581756127
1992	47.53767282895759
1993	48.603625673689365
1994	47.40009257830582
1995	48.871582962492056
1996	47.94563349476644
1997	50.48037778863377
1998	64.30191792122088
1999	70.99644128113879
2000	70.95282146160962
2001	67.8237650200267
2002	67.28131324488419
2003	67.0737222976029
2004	65.1525126179504
2005	67.49197615772582
2006	66.51583710407239
2007	63.52324819908317
2008	64.68163078332569