Year maximum value in 2004 = 100 2006 3.6898909439 2007 2.7269257302 2008 2.5935002746 2009 2.7124495922 2010 3.9358186431 2011 6.5939591525 2012 6.4225039595 2013 6.5720046323 2014 5.4798632398 2015 5.7376939426 2016 6.0523511253 2017 5.7478169368 2018 5.6497532034 2019 6.0492369451 2020 4.9362990495 2021 4.8535970084