Year maximum value in 2004 = 100 2006 15.2380422881 2007 16.7493417929 2008 15.4341091745 2009 16.4969489127 2010 13.4832128224 2011 14.4379041431 2012 13.6455360717 2013 13.8238010552 2014 14.0182795776 2015 16.6148453051 2016 16.67368058 2017 18.6591155682 2018 17.0942938673 2019 16.8825451148 2020 17.0321028723 2021 17.5368934006