Year	% of total
1970	89.08967085174719
1971	88.49585442595907
1972	88.97961617195497
1973	88.69379521565337
1974	88.77756541673489
1975	89.02348679881322
1976	89.28050482311218
1977	89.87161990468212
1978	89.14393853223532
1979	88.47385850453686
1980	87.1076753002494
1981	87.01082260899143
1982	87.17420406370867
1983	87.27477786651455
1984	87.0386060192685
1985	87.0398134859166
1986	87.02348865685049
1987	87.39773347897325
1988	86.38384044784873
1989	86.95235244284488
1990	91.56829679595279
1991	90.31657355679702
1992	90.20332717190388
1993	88.75
1994	89.1566265060241
1995	86.28230616302187
1996	86.61290322580645
1997	84.16801292407108
1998	82.90468986384266
1999	81.62083936324169
2000	78.60394537177542
2001	80.24132730015083
2002	79.421768707483
2003	80.8695652173913
2004	83.02207130730051
2005	84.24778761061947
2006	83.27338129496404
2007	83.39100346020761
2008	83.21917808219177