Year maximum value in 2004 = 100 2006 4.162771181 2007 4.3099637325 2008 2.7661026785 2012 3.9223224835 2014 2.5927955202 2015 2.5927955202 2016 2.5927955202 2017 2.5927955202 2018 4.1931862026 2019 4.1931862026 2020 4.3569405011 2021 3.4628606755