Year Percent 1960-01-01 93.09620000000000 1961-01-01 94.36570000000000 1962-01-01 95.81760000000000 1963-01-01 96.44640000000000 1964-01-01 96.23520000000000 1965-01-01 96.03680000000000 1966-01-01 96.77030000000000 1967-01-01 98.85900000000000 1968-01-01 98.85900000000000 1969-01-01 99.24220000000000 1970-01-01 99.89690000000000 1971-01-01 99.89690000000000 1972-01-01 99.89690000000000 1973-01-01 99.99470000000000 1974-01-01 97.73730000000000 1975-01-01 95.83130000000000 1976-01-01 96.65230000000000 1977-01-01 97.79820000000000 1978-01-01 96.97680000000000 1979-01-01 93.21450000000000 1980-01-01 89.05550000000000 1981-01-01 87.38720000000000 1982-01-01 89.19510000000000 1983-01-01 90.48990000000000 1984-01-01 90.55890000000000 1985-01-01 89.87920000000000 1986-01-01 90.94060000000000 1987-01-01 92.08180000000000 1988-01-01 92.04110000000000 1989-01-01 94.42100000000000 1990-01-01 94.97330000000000 1991-01-01 93.47240000000000 1992-01-01 91.52090000000000 1993-01-01 90.88260000000000 1994-01-01 92.10570000000000 1995-01-01 91.34490000000000 1996-01-01 91.15560000000000 1997-01-01 92.45980000000000 1998-01-01 93.01390000000000 1999-01-01 93.91990000000000 2000-01-01 93.81380000000000 2001-01-01 93.75190000000000 2002-01-01 92.96610000000000 2003-01-01 92.41799999999999 2004-01-01 92.84510000000000 2005-01-01 93.48480000000000 2006-01-01 94.14550000000000 2007-01-01 95.00930000000000 2008-01-01 95.80280000000000 2009-01-01 99.46700000000001 2010-01-01 99.49530000000000 2011-01-01 99.51930000000000 2012-01-01 99.60320000000000 2013-01-01 99.62440000000000 2014-01-01 99.57860000000000 2015-01-01 99.48530000000000 2016-01-01 99.40230000000000