Year maximum value in 2004 = 100 2006 7.643580608 2007 8.5879706306 2008 9.203258023 2009 9.384443851 2010 7.1392173473 2011 8.383930746 2012 8.2905179134 2013 7.5525348066 2014 7.949612716 2015 10.4663559007 2016 8.2900254337 2017 27.3417284307 2018 34.6985263213 2019 34.0499184712 2020 36.8528126453 2021 37.7257468078