Year maximum value in 2004 = 100 2006 4.0679150546 2007 4.9895082163 2008 6.046222391 2009 6.3770194602 2010 6.0202024796 2011 6.2091370574 2012 11.0918899788 2013 10.570588209 2014 10.0381380198 2015 8.0314344808 2016 6.6632665137 2017 6.3476089175 2018 6.8081888475 2019 6.5002846081 2020 6.1684059711 2021 6.6432101656