Year	Months
2004-01-01	2.81369408770466
2005-01-01	4.26280544429538
2006-01-01	4.23966079076534
2007-01-01	4.33508678253818
2008-01-01	3.34021822169237
2009-01-01	3.43209177036123
2010-01-01	1.64517780450222
2011-01-01	1.79938112743731
2012-01-01	2.20255954996111
2013-01-01	1.97615563450183
2014-01-01	3.55375250088749
2015-01-01	4.99221017574092
2016-01-01	3.52970273857984
2017-01-01	3.32816178106851
2018-01-01	3.30957107944462
2019-01-01	3.54402860380366