Year maximum value in 2004 = 100 2006 8.3961747929 2007 8.692505959 2008 8.3622753858 2009 6.3864962938 2010 5.9845347568 2011 5.8906739378 2012 6.4133642186 2013 6.6453846819 2014 5.9945136326 2015 5.9929272772 2016 7.3322384692 2017 6.1459376324 2018 7.4707401283 2019 7.7719277886 2020 8.0629768768 2021 8.6267393294