Year	% of total
1970	71.0010209480313
1971	71.04847779084736
1972	70.97905445003619
1973	70.5171129579049
1974	70.05314579586751
1975	70.65686584215386
1976	71.82939295161115
1977	71.9459648618057
1978	72.2859854536923
1979	72.98422452048892
1980	72.36123404148462
1981	70.06943938297816
1982	72.53550638850116
1983	75.77231045066583
1984	75.39890028895516
1985	75.55678772441814
1986	75.14157060570776
1987	75.73039759376829
1988	75.25765190170573
1989	72.98131071782988
1990	38.09310653536258
1991	37.3956326268465
1992	38.67348622339548
1993	40.09193054136874
1994	40.46183008788557
1995	40.92670894996476
1996	41.74861433935276
1997	41.13742375313958
1998	40.25051411478781
1999	40.80854309687262
2000	41.073170731707314
2001	44.93192133131619
2002	43.8487034509651
2003	44.44659817794146
2004	45.555990602975726
2005	45.90450310559006
2006	45.98413005612541
2007	45.22593320235757
2008	45.90747330960854