Year maximum value in 2004 = 100 2006 4.5814181384 2007 5.0543646046 2008 4.6373910356 2009 4.3521638223 2010 5.9994747697 2011 5.6977016942 2012 5.2852173554 2013 6.1619022042 2014 6.7276872881 2015 8.7813995513 2016 8.7942186903 2017 8.046164135 2018 8.5656949434 2019 8.1395779774 2020 9.3621973016 2021 8.1260985113