Year maximum value in 2004 = 100 2006 16.667048508 2007 16.6995783085 2008 18.8724203544 2009 19.8675497977 2010 20.349238435 2011 20.5144801356 2012 19.9416901125 2013 21.4302034565 2014 21.714283643 2015 22.7546413984 2016 20.6238379517 2017 19.5846188798 2018 20.084039529 2019 36.6509751579 2020 39.9862068986 2021 37.1852140752