Year	% of total
1970	79.45132033312767
1971	78.877412993105
1972	78.04903250823013
1973	77.09300563211764
1974	76.57507759554304
1975	76.65845927944
1976	76.05247794188026
1977	76.93847672503456
1978	76.31567765236952
1979	74.60405574122666
1980	74.65187765244859
1981	73.40511665495092
1982	72.61802509391174
1983	73.56601881617871
1984	73.4459883263349
1985	73.18998331889978
1986	72.13205529579157
1987	71.71664446564411
1988	71.31647238305744
1989	70.57629700896298
1990	78.26086956521739
1991	76.59574468085107
1992	76.59574468085107
1993	77.08333333333334
1994	76
1995	75.92592592592592
1996	76.78571428571429
1997	74.13793103448276
1998	74.57627118644068
1999	74.19354838709677
2000	73.01587301587301
2001	71.875
2002	71.875
2003	71.875
2004	72.3076923076923
2005	71.21212121212122
2006	70.76923076923077
2007	69.6969696969697
2008	69.6969696969697