Year	% of total
1970	93.75051054748607
1971	93.45142969238962
1972	93.30157040598617
1973	93.21007806955288
1974	92.71359824454682
1975	92.66506743326276
1976	92.45477826457797
1977	92.140874934236
1978	92.42413437920925
1979	92.84493905233721
1980	92.1336261532509
1981	91.78212509270926
1982	91.83164432488066
1983	91.87374914177825
1984	91.80039900145184
1985	91.90049028135337
1986	91.41732697415885
1987	90.87387703878736
1988	91.50289028414826
1989	91.79403571996394
1990	92.05607476635514
1991	89.8876404494382
1992	90.625
1993	91.30434782608695
1994	90.54726368159204
1995	89.94708994708994
1996	89.07103825136612
1997	89.0625
1998	88.94736842105263
1999	89.67136150234741
2000	89.90825688073394
2001	89.44954128440367
2002	89.91596638655463
2003	90.6614785992218
2004	90.04149377593362
2005	90.42145593869732
2006	90
2007	90.34749034749035
2008	89.88326848249028