Year maximum value in 2004 = 100 2006 16.1929506932 2007 19.4702604005 2008 19.5629916642 2009 19.8142441033 2010 19.8380426613 2011 24.0317340751 2012 24.1880407026 2013 25.1481509644 2014 26.204618433 2015 25.7066926469 2016 24.2942227833 2017 28.1794796318 2018 27.5124493353 2019 27.2302724674 2020 27.8453440579 2021 28.1617431568