Year	% of total
1970	63.4173457237614
1971	62.977980457473635
1972	57.356172037586695
1973	61.412878444694485
1974	62.51050037591932
1975	62.09967339964943
1976	60.98301871489753
1977	61.270494427837164
1978	61.29061488282845
1979	58.74507601917636
1980	57.09966961690682
1981	54.56907805250084
1982	54.01616738124797
1983	53.07913884230492
1984	53.793448486659756
1985	49.89032995132822
1986	48.462028440837436
1987	47.65157797619936
1988	50.53361847733058
1989	51.446631951373604
1990	42.85444591278082
1991	44.97598817879572
1992	45.78041786153216
1993	42.38105678579259
1994	40.745824754060855
1995	39.71875829132396
1996	41.05920856887831
1997	42.17550884217551
1998	44.932308818148556
1999	42.473794549266245
2000	48.612153038259564
2001	51.11415838189921
2002	42.40545567265964
2003	49.512425290972004
2004	48.40425531914894
2005	46.208742194469224
2006	47.38589211618257
2007	49.528824833702885
2008	51.84996172492983