Year	% of total
1970	83.42756200144036
1971	83.25954060957852
1972	82.95275947756775
1973	83.93679533587765
1974	81.59132022861864
1975	82.57160841991808
1976	82.74001487232711
1977	83.81339667402503
1978	82.21295927968877
1979	83.17981602043483
1980	85.04557915508943
1981	83.58546826247412
1982	84.90032120920912
1983	83.77072459685597
1984	83.64584572290792
1985	82.39237095446764
1986	81.5041776108022
1987	81.54094492618843
1988	80.37446608366679
1989	81.19462794328084
1990	86.02664844550735
1991	86.15894039735099
1992	86.94325808419768
1993	87.55707762557078
1994	87.90911549905329
1995	87.95244385733157
1996	88.45070422535211
1997	88.94684550422255
1998	89.57839886309806
1999	89.99769532150265
2000	90.57764111574785
2001	89.01906730990122
2002	88.4942253214208
2003	87.86540483701367
2004	87.16216216216216
2005	86.68767231193382
2006	85.50782818145322
2007	85.26699961582788
2008	84.47584494939852