Year	% of total
1970	90.70398767907992
1971	90.8420693545063
1972	90.82812253608485
1973	90.59260511159673
1974	90.42417583570756
1975	90.61277349737176
1976	90.2693191409547
1977	90.05503711344377
1978	90.51835155553472
1979	91.36046686517855
1980	90.21391087384848
1981	90.1204046743863
1982	90.86415012640289
1983	91.5185207579979
1984	91.34392433459779
1985	90.9542954764159
1986	90.85649904980242
1987	90.67763935515788
1988	91.09522049514702
1989	91.10749798769862
1990	92.2211808809747
1991	91.67473378509197
1992	91.54518950437318
1993	91.17647058823529
1994	91.00580270793037
1995	90.77526987242395
1996	90.12219959266803
1997	89.77505112474438
1998	89.91097922848664
1999	90.17941454202078
2000	89.27125506072875
2001	88.9
2002	88.8673765730881
2003	89.0497737556561
2004	89.17748917748918
2005	88.80208333333334
2006	87.93879387938794
2007	91.81008902077151
2008	91.52843601895735