Year	Months
2004-01-01	2.40143622298485
2005-01-01	2.76774758688374
2006-01-01	2.84670663455950
2007-01-01	3.48549450741506
2008-01-01	4.53695887894747
2009-01-01	4.13102831754881
2010-01-01	3.40548441615336
2011-01-01	3.68385333227037
2012-01-01	3.96807817787941
2013-01-01	4.47727541644471
2014-01-01	7.38946403685528
2015-01-01	6.04972193623462
2016-01-01	6.05032926767100
2017-01-01	5.20200756430673
2018-01-01	5.19805926598448
2019-01-01	4.78931784003261