Year maximum value in 2004 = 100 2006 4.6696087485 2007 3.9776478102 2008 4.4299386332 2009 3.5994190843 2010 3.5503784762 2011 3.7500523289 2012 5.6531738469 2013 5.5364783478 2014 5.173252307 2015 4.8740214253 2016 6.3746238152 2017 6.8703897686 2018 4.0399916518 2019 6.5845321799 2020 6.7351654245 2021 7.2124081079