Year maximum value in 2004 = 100 2006 4.9863937629 2007 7.4333549214 2008 6.007406292 2009 6.0271814112 2010 5.3215889007 2011 4.6593203154 2012 7.3366090947 2013 7.2502026888 2014 7.7514269581 2015 7.9861244117 2016 7.1487684823 2017 7.6666993552 2018 7.670323987 2019 7.8415695324 2020 7.4337942745 2021 6.5608442926