Year	%
1971	90.88152
1972	89.97155
1973	88.19092
1974	87.30197
1976	85.29237
1977	84.12535
1978	84.19883
1979	81.68584
1980	82.87536
1981	84.31396
1982	85.72175
1983	86.52975
1984	87.28804
1985	87.32891
1986	85.51156
1987	83.25375
1988	81.45607
1989	81.91895
1990	79.11637
1991	77.27537
1992	71.81948
1993	73.11743
1998	74.29101
1999	73.49223
2000	75.44009
2001	77.46219
2002	94.41357
2003	97.41058
2004	98.56596
2005	98.34328
2006	98.48826
2007	98.61481
2008	97.23851
2009	98.03536
2010	98.72956
2011	97.93488
2012	57.20027