Year maximum value in 2004 = 100 2006 7.0003665092 2007 6.085981441 2008 6.1813598155 2009 6.3819477545 2010 7.5689403363 2011 8.542981605 2012 9.215000521 2013 8.8907513715 2014 10.5945834977 2015 9.2297259284 2016 8.2212943322 2017 7.9073926372 2018 8.4298213853 2019 8.7376270542 2020 8.4593232969 2021 8.5430179607