Year	% of total
1970	88.83488226248471
1971	90.82701686397535
1972	90.91963495021919
1973	90.69965210521748
1974	91.67783340241184
1975	91.0746615073391
1976	91.86007449788426
1977	91.40532807305988
1978	90.96911699743582
1979	89.90667876084024
1980	90.69396262422352
1981	91.34717078026378
1982	90.83727433480634
1983	90.70012076146796
1984	91.73619510153611
1985	91.20837942808777
1986	91.22852415465299
1987	89.85058057529565
1988	91.47851405867472
1989	91.0484663189435
1990	94.57202505219206
1991	93.93939393939394
1992	93.55555555555556
1993	93.16628701594533
1994	92.98245614035088
1995	93.0327868852459
1996	93.53146853146853
1997	92.66055045871559
1998	91.33064516129032
1999	90.55441478439425
2000	89.59660297239915
2001	91.70984455958549
2002	91.9732441471572
2003	78.96995708154506
2004	81.53846153846153
2005	84.44444444444444
2006	87.88598574821853
2007	83.125
2008	92.7367055771725