Year	Months
2004-01-01	4.72616086476870
2005-01-01	3.45471003896684
2006-01-01	3.00622450088861
2007-01-01	3.47168681658635
2008-01-01	4.21174965186183
2009-01-01	4.51391312189721
2010-01-01	4.22656109536001
2011-01-01	4.41708950298368
2012-01-01	4.97717112013641
2013-01-01	5.32865372555185
2014-01-01	6.94819841769753
2015-01-01	7.89851253226086
2016-01-01	8.25641721620003
2017-01-01	9.25111139590128
2018-01-01	9.10021338699574
2019-01-01	8.99822894140650