Year maximum value in 2004 = 100 2006 7.9201772197 2007 8.720313515 2008 7.5392928438 2009 10.9524546627 2010 17.0302445449 2011 16.8424187598 2012 16.7564050035 2013 23.1018607732 2014 23.0730112961 2015 21.4290483364 2016 10.6873473635 2017 30.1916172547 2018 29.7320186909 2019 9.3094660098 2020 25.1249649889 2021 31.7069459582