Year	% of total
1970	69.74905671358668
1971	68.92884043473559
1972	69.29694951336835
1973	70.09132270908178
1974	67.77026799281668
1975	69.09306909770734
1976	69.63554799614772
1977	70.63599723118055
1978	69.24010043993755
1979	69.61924069842489
1980	70.69538045270419
1981	68.88323562592518
1982	70.59485077226803
1983	69.45510329375931
1984	69.70981425088951
1985	68.99302742170879
1986	69.63017365155332
1987	70.2649909270217
1988	70.90727903723732
1989	71.58299464085292
1990	85.34482758620689
1991	83.92857142857143
1992	83.01886792452831
1993	82.0754716981132
1994	80.95238095238095
1995	79
1996	80.3921568627451
1997	81.73913043478261
1998	88.18897637795276
1999	82.90598290598291
2000	81.3953488372093
2001	78.99159663865547
2002	80.91603053435115
2003	80.2919708029197
2004	77.41935483870968
2005	82.84023668639054
2006	79.59183673469387
2007	76.69172932330827
2008	77.93103448275862