Year	% of total
1970	81.53808714683302
1971	88.92998607537554
1972	86.75427358584142
1973	79.72325702392246
1974	89.49380601745959
1975	87.19299301749291
1976	87.00240409365841
1977	80.27634628040794
1978	76.17035657573297
1979	80.75237188431781
1980	74.4727393145584
1981	78.29803893049862
1982	77.75439398036703
1983	66.92514923117305
1984	76.97450871726133
1985	83.32809806698087
1986	79.13547579290177
1987	73.60515759491076
1988	78.05141550909485
1989	83.30264707886664
1990	92.37668161434978
1991	93.15217391304348
1992	93.22974472807991
1993	93.36332958380203
1994	93.37142857142857
1995	93.83634431455899
1996	93.9879759519038
1997	94.20702754036088
1998	94.27516158818098
1999	94.49378330373001
2000	94.48336252189142
2001	93.55828220858896
2002	92.0754716981132
2003	92.09535759096612
2004	91.73228346456693
2005	92.47311827956989
2006	92.7038626609442
2007	92.56120527306967
2008	91.5050784856879