Year maximum value in 2004 = 100 2006 17.6945941637 2007 17.6806520959 2008 13.4702216967 2009 13.8182155495 2010 12.6004810619 2011 11.4740841781 2012 11.6590255637 2013 10.994087756 2014 10.3613645605 2015 10.3940867075 2016 12.50867481 2017 12.8138476281 2018 12.4905013643 2019 13.9351673636 2020 13.0729219083 2021 12.7838867846