Year	% of total
1970	89.34079132703891
1971	88.5597661959556
1972	88.43866980109574
1973	88.15225637605555
1974	87.8425045330033
1975	87.92103468428391
1976	87.20530418664278
1977	86.86589962191388
1978	86.74291389784932
1979	86.44221548617482
1980	85.19267889285165
1981	84.90583631703176
1982	84.40699203325526
1983	82.98933291589759
1984	82.71104647654563
1985	82.57240534917239
1986	82.1876338315119
1987	81.29357718362947
1988	80.52845537976404
1989	80.27827061037715
1990	78.19198508853681
1991	77.72261867825007
1992	77.44811683320523
1993	76.98449255335483
1994	76.7970882620564
1995	76.82615869206539
1996	76.45462767561048
1997	76.40466228332336
1998	76.00421242665864
1999	76.43013899049012
2000	76.37075718015666
2001	76.14971710430872
2002	75.80805923394561
2003	75.32723434201267
2004	74.43800367595081
2005	74.26755113322278
2006	74.1776989217961
2007	74.00595077089532
2008	74.44386286312483