Year	% of total
1970	87.41978010660468
1971	87.57927727990017
1972	88.2703854700072
1973	88.22527955738262
1974	87.82030323700796
1975	86.94738966304418
1976	85.55781089619023
1977	83.89393087501887
1978	82.31729412216418
1979	79.34797661011271
1980	77.78979590454207
1981	77.71682563199917
1982	77.95246809835601
1983	78.5741433245138
1984	79.56644254041889
1985	79.5275047175932
1986	79.85313036490969
1987	80.1700640831202
1988	79.67954229033786
1989	80.67632326519902
1990	93.93939393939394
1991	94.87179487179486
1992	94.87179487179486
1993	95.1219512195122
1994	95.65217391304348
1995	93.75
1996	92.15686274509804
1997	92
1998	92.3076923076923
1999	93.02325581395348
2000	93.87755102040816
2001	40.78947368421053
2002	25.94142259414226
2003	19.26605504587156
2004	12.903225806451612
2005	12.424849699398797
2006	12.172284644194757
2007	11.367673179396093
2008	11.185308848080133