Year	% of total
1970	86.23941767915427
1971	85.90544312153233
1972	85.38153100747452
1973	85.46100528117614
1974	84.2595092630273
1975	83.73558512517411
1976	83.45416284933536
1977	83.8295003184151
1978	82.97880828271482
1979	83.00302061399009
1980	83.43611355123802
1981	82.32919654565286
1982	82.57310512583055
1983	82.1677914672867
1984	81.2913555951891
1985	81.11127455762279
1986	81.5565107287035
1987	80.58327075660033
1988	80.00231941166366
1989	80.67250467580067
1990	84.63618485742379
1991	81.95595548188491
1992	79.6408529741863
1993	74.92252681764005
1994	72.67308574048602
1995	70.5267837297177
1996	69.85897705746159
1997	69.10405785456007
1998	69.58934517203107
1999	67.98390047566777
2000	65.33358250794244
2001	65.98529675452752
2002	68.4775536759922
2003	67.30546836279531
2004	67.18623153109272
2005	67.75152558285087
2006	68.53448275862068
2007	70.3481228668942
2008	70.76115485564304