Year	Ratio
2005-01-01	66.72
2006-01-01	63.48
2007-01-01	60.22
2008-01-01	60.29
2009-01-01	60.44
2010-01-01	57.67
2011-01-01	56.62
2012-01-01	56.34
2013-01-01	54.92
2014-01-01	53.66
2015-01-01	52.60
2016-01-01	52.81
2017-01-01	52.50