Year	% of total
1970	93.46393817669123
1971	93.49506670188879
1972	93.50266003546713
1973	93.51731135359506
1974	93.4827193117749
1975	93.31656346373329
1976	93.24805794133422
1977	92.98773087655577
1978	93.00436012967748
1979	92.6069620744733
1980	92.26372082647121
1981	92.3978398480241
1982	92.34053592186707
1983	92.41822772443777
1984	92.45891404063877
1985	92.65125246298861
1986	92.66903925257483
1987	92.5183282278862
1988	92.38501313277185
1989	92.59632635612569
1990	97.54098360655738
1991	71.25748502994011
1992	56.74418604651162
1993	41.596638655462186
1994	35.66433566433567
1995	31.024096385542173
1996	34.68208092485549
1997	38.227146814404435
1998	40.05449591280654
1999	41.14441416893733
2000	42.318059299191376
2001	41.27906976744186
2002	42.24924012158054
2003	44.23676012461059
2004	46.30225080385852
2005	48.68421052631579
2006	45.9546925566343
2007	46.08433734939759
2008	44.44444444444444