Year	Percent
1991-01-01	69.9660034179688
1992-01-01	69.3880004882813
1993-01-01	68.5899963378906
1994-01-01	68.4530029296875
1995-01-01	68.8629989624023
1996-01-01	68.5630035400391
1997-01-01	69.0199966430664
1998-01-01	69.3840026855469
1999-01-01	69.4940032958984
2000-01-01	69.8560028076172
2001-01-01	70.1200027465820
2002-01-01	70.3909988403320
2003-01-01	70.5429992675781
2004-01-01	70.6900024414063
2005-01-01	70.6159973144531
2006-01-01	70.7490005493164
2007-01-01	70.5940017700195
2008-01-01	70.5279998779297
2009-01-01	70.4049987792969
2010-01-01	70.1940002441406
2011-01-01	69.3119964599609
2012-01-01	68.9789962768555
2013-01-01	68.7870025634766
2014-01-01	68.4079971313477
2015-01-01	68.1650009155273
2016-01-01	68.1360015869141
2017-01-01	68.0530014038086