Year	% of total
1970	76.49556685038277
1971	76.9973818300975
1972	76.92001622642098
1973	75.98012477005518
1974	76.22328019855019
1975	76.28795274020015
1976	76.44716943559399
1977	77.7714405677755
1978	77.32358559957501
1979	77.2833831274984
1980	76.0783407156587
1981	76.06454135191879
1982	76.15332702877505
1983	76.10938884078621
1984	75.22963917770048
1985	75.43606740034653
1986	75.69913263013372
1987	76.15305957851233
1988	75.10152239352607
1989	75.43018707287328
1990	92.50913520097443
1991	92.79488669378269
1992	92.86122215876642
1993	92.95695919508104
1994	93.14994606256742
1995	93.43765774861181
1996	93.32023575638507
1997	92.90744466800804
1998	92.62418464626192
1999	92.7796130250118
2000	92.60299625468164
2001	92.48395967002749
2002	92.45535714285714
2003	92.0656634746922
2004	91.88576609247507
2005	91.98423127463863
2006	92.16261525565801
2007	92.06680584551148
2008	92.54706108336535