Year	% of total
1970	95.72914752462715
1971	95.6939209547313
1972	95.50502791667273
1973	95.65156863014074
1974	95.51944588685433
1975	95.34968343264205
1976	94.78345391131042
1977	94.63888234437664
1978	94.4881312761473
1979	93.79344613394515
1980	93.85641819767267
1981	93.4194809361907
1982	92.79464003313502
1983	92.99135046748565
1984	93.74880837348218
1985	93.75658109828194
1986	93.76076189757521
1987	93.60198489019623
1988	93.29652791328596
1989	93.54017250893736
1990	91.30434782608695
1991	93.61702127659575
1992	91.83673469387756
1993	90.47619047619048
1994	90.69767441860465
1995	90.9090909090909
1996	88.88888888888889
1997	90.9090909090909
1998	90.9090909090909
1999	90.47619047619048
2000	88.09523809523809
2001	89.47368421052632
2002	87.5
2003	90.47619047619048
2004	88.09523809523809
2005	90.69767441860465
2006	87.5
2007	90.69767441860465
2008	88.37209302325581