Year	% of total
1970	35.351454531734
1971	33.804629793701494
1972	32.964907205157054
1973	32.99146076185521
1974	33.226530035016374
1975	34.763750996178686
1976	33.84889430005617
1977	33.68768230381079
1978	34.25601099678887
1979	35.13489276312637
1980	41.33458265504055
1981	42.49845124002587
1982	44.7608245646129
1983	47.075337630969884
1984	47.98885814049964
1985	49.051483850384955
1986	50.41510248813079
1987	41.60759818838135
1988	48.48842334512546
1989	51.29534454025389
1990	55.79288025889968
1991	55.57692307692308
1992	55.13720485003191
1993	52.585669781931465
1994	53.870558375634516
1995	54.90578297595842
1996	54.66405740378343
1997	54.08095554080955
1998	53.288135593220346
1999	54.41379310344827
2000	53.41880341880342
2001	55.41448842419716
2002	55.8846453624318
2003	55.16969218626677
2004	53.23308270676692
2005	52.865761689291105
2006	53.186646433990894
2007	57.98462852263023
2008	83.71810449574727