Year maximum value in 2004 = 100 2006 6.6430616383 2007 3.8295442155 2008 5.8387455843 2009 6.341457695 2010 6.5627237836 2011 6.9883205746 2012 8.1476889968 2013 8.7285540924 2014 9.3293994197 2015 10.556902079 2016 11.549036834 2017 9.0140980475 2018 10.7327348337 2019 10.9737305996 2020 9.2595097607 2021 8.6811645566