Year maximum value in 2004 = 100 2006 4.4729714562 2007 4.1637771496 2008 5.3148580334 2009 4.3573893029 2010 5.9076133104 2011 5.9332702953 2012 5.3488733379 2013 5.7592655423 2014 5.5528728493 2015 5.3949936805 2016 4.9589855971 2017 6.175790169 2018 6.8352400597 2019 6.4679952817 2020 6.1722081911 2021 5.9503179328