Year	% of total
1970	75.96710540610559
1971	75.45492186763215
1972	74.96156448791838
1973	74.92591912544697
1974	74.83788419272715
1975	74.75340277251725
1976	76.06863809370644
1977	75.23294725275403
1978	75.84620869502723
1979	76.1662131404965
1980	75.24858143616463
1981	75.95396714208341
1982	77.18990020532158
1983	67.34910135900222
1984	69.65809859676992
1985	68.08647864298523
1986	66.6890635989149
1987	68.19511899850393
1988	68.91474680737049
1989	68.42893392286457
1990	84.90566037735849
1991	83.47107438016529
1992	84.95575221238938
1993	88.03418803418803
1994	91.97080291970804
1995	94.73684210526315
1996	93.27731092436974
1997	92.03539823008849
1998	92.3076923076923
1999	91.96428571428571
2000	91.52542372881356
2001	90.43478260869566
2002	92.24806201550388
2003	91.6030534351145
2004	91.33858267716536
2005	90.625
2006	90.1639344262295
2007	90.1639344262295
2008	90.35087719298247