Year	% of total
1970	89.38447836647644
1971	89.352987442395
1972	89.55307820299502
1973	88.81445303768609
1974	88.42080008587685
1975	88.0234260202194
1976	87.29775162998823
1977	87.01142999522727
1978	87.25690254096547
1979	87.58947354726236
1980	87.46191763825296
1981	88.02828427375744
1982	87.49441576989088
1983	86.76269010532953
1984	87.4014562362846
1985	87.92524319900099
1986	88.44773963963415
1987	88.58160271739958
1988	89.31154421881851
1989	88.90355539806282
1990	91.1504424778761
1991	91.07142857142857
1992	90.75630252100841
1993	90.9090909090909
1994	89.83050847457628
1995	90.5982905982906
1996	90.9090909090909
1997	91.07142857142857
1998	90.43478260869566
1999	90.990990990991
2000	90.9090909090909
2001	91.73553719008265
2002	91.73553719008265
2003	91.2
2004	90.1639344262295
2005	90.2439024390244
2006	89.68253968253968
2007	88.6178861788618
2008	89.84375