Year	% of total
1970	86.98856152091994
1971	87.49651214665205
1972	87.5651499629267
1973	87.22415018426287
1974	86.42170647859894
1975	86.02609357327695
1976	85.71593337055104
1977	85.97273276188004
1978	85.63198132461378
1979	85.5632931694967
1980	84.58574101941882
1981	85.4291756070017
1982	84.5694612738031
1983	84.16389328835592
1984	84.0828991054809
1985	83.6792761941938
1986	84.62209332802955
1987	84.19858685608148
1988	83.75058610966971
1989	83.34429950397205
1990	89.69072164948454
1991	90.29126213592234
1992	90.51724137931035
1993	89.28571428571429
1994	88.49557522123894
1995	87.82608695652175
1996	84.5528455284553
1997	88
1998	88.54961832061069
1999	88.63636363636364
2000	89.65517241379311
2001	89.65517241379311
2002	89.04109589041096
2003	89.1156462585034
2004	88.43537414965986
2005	88.51351351351352
2006	87.83783783783784
2007	88
2008	87.33333333333333