Year	% of total
1970	49.95385152546009
1971	51.424743054813824
1972	51.690397398053115
1973	50.089814723709836
1974	49.5311483085218
1975	51.35776489739106
1976	50.77270376991476
1977	50.106981741697965
1978	47.98424848387959
1979	43.33025920951101
1980	44.28565327103504
1981	43.942917382732574
1982	47.16343018408628
1983	47.23761280564659
1984	47.927483487640174
1985	50.45596262258599
1986	49.46480522886717
1987	51.26675503849374
1988	49.23842930838461
1989	50.12619022909106
1990	86.45833333333334
1991	86.9767441860465
1992	86.44859813084112
1993	86.81818181818181
1994	78.6046511627907
1995	75.46296296296296
1996	76.7175572519084
1997	72.33201581027669
1998	72.14285714285714
1999	71.28378378378379
2000	69.6078431372549
2001	69.63696369636963
2002	68.91891891891892
2003	69.93464052287581
2004	70.7936507936508
2005	71.73913043478261
2006	70.80745341614907
2007	71.34328358208955
2008	69.84615384615384