Year maximum value in 2004 = 100 2006 24.1071657673 2007 24.3256958378 2008 23.9899007104 2009 24.7535903239 2010 24.8983997437 2011 26.1658015064 2012 28.1527309935 2013 29.9534470774 2014 27.7960592424 2015 27.2797720453 2016 35.6073289168 2017 38.2677742813 2018 38.5069290184 2019 38.1600903297 2020 38.2614847573 2021 42.2284050886