Year	% of total
1970	92.32133542574464
1971	91.98636959268065
1972	91.84620247288035
1973	91.74036096711944
1974	91.69108545171133
1975	91.57800623864632
1976	91.32287080865757
1977	90.77787968118791
1978	90.55193685699416
1979	89.68365560339222
1980	89.30369820663995
1981	88.99029818675834
1982	88.24524016980226
1983	87.69891396292421
1984	86.95860249102805
1985	86.4434395602699
1986	85.68818266873892
1987	84.98903020542213
1988	84.6937135603141
1989	83.81343620073784
1990	100
1991	100
1992	100
1993	100
1994	100
1995	100
1996	80
1997	80
1998	100
1999	100
2000	80
2001	80
2002	100
2003	80
2004	80
2005	80
2006	80
2007	80
2008	100