Year	Percent
1991-01-01	59.7659988403320
1992-01-01	59.7260017395020
1993-01-01	59.6800003051758
1994-01-01	59.4710006713867
1995-01-01	59.2340011596680
1996-01-01	59.2000007629395
1997-01-01	59.2330017089844
1998-01-01	59.2379989624023
1999-01-01	59.2519989013672
2000-01-01	59.2350006103516
2001-01-01	59.2639999389648
2002-01-01	59.2309989929199
2003-01-01	59.3390007019043
2004-01-01	59.3030014038086
2005-01-01	61.0379981994629
2006-01-01	62.8470001220703
2007-01-01	64.6360015869141
2008-01-01	66.4469985961914
2009-01-01	68.3209991455078
2010-01-01	70.1119995117188
2011-01-01	72.1330032348633
2012-01-01	72.1750030517578
2013-01-01	72.1800003051758
2014-01-01	72.1579971313477
2015-01-01	72.0999984741211
2016-01-01	71.6760025024414
2017-01-01	71.2900009155273