Year	Percent
1991-01-01	67.7720031738281
1992-01-01	67.7139968872070
1993-01-01	67.6240005493164
1994-01-01	67.5080032348633
1995-01-01	67.4049987792969
1996-01-01	67.3700027465820
1997-01-01	67.2669982910156
1998-01-01	67.1809997558594
1999-01-01	67.0869979858398
2000-01-01	67.0110015869141
2001-01-01	67.0009994506836
2002-01-01	66.9670028686523
2003-01-01	66.9459991455078
2004-01-01	66.8740005493164
2005-01-01	66.8320007324219
2006-01-01	66.9150009155273
2007-01-01	66.9769973754883
2008-01-01	67.0169982910156
2009-01-01	67.0149993896484
2010-01-01	66.9639968872070
2011-01-01	67.1320037841797
2012-01-01	67.2190017700195
2013-01-01	67.3339996337891
2014-01-01	67.2379989624023
2015-01-01	67.0759963989258
2016-01-01	67.0780029296875
2017-01-01	67.2180023193359