Year	% of total
1970	90.86783963720792
1971	90.6001081476409
1972	90.73468433289163
1973	90.8232559252134
1974	90.69127528055486
1975	90.6418292070995
1976	90.270687828764
1977	90.15282844667838
1978	90.48254374298202
1979	90.95059420332488
1980	90.91554680780195
1981	91.31711048869893
1982	90.98743779767679
1983	90.74102975996676
1984	90.61679260796399
1985	90.39893168003098
1986	90.28103894770638
1987	89.77971775698357
1988	89.6275123789885
1989	88.8823426161087
1990	85.22692659153213
1991	85.01396214706794
1992	84.55997494519261
1993	84.39070351758794
1994	84.89472078120231
1995	84.91353607632678
1996	83.82441371016236
1997	84.0131973605279
1998	83.51145038167938
1999	83.2579185520362
2000	82.72476219699294
2001	82.69464720194647
2002	83.040761678072
2003	83.94182249925794
2004	84.02736466389054
2005	84.06315162347335
2006	84.12651492757908
2007	84.37406632805498
2008	83.91502276176024