Year maximum value in 2004 = 100 2006 7.7354532376 2007 8.6463020636 2008 7.6765416045 2009 10.8855983026 2010 9.9762801626 2011 11.2910368953 2012 11.038700943 2013 13.5410576196 2014 13.2794294733 2015 16.8003269471 2016 18.4266047292 2017 19.1441997628 2018 10.0265660128 2019 8.9116560094 2020 9.5230670592 2021 8.3825033537