Year maximum value in 2004 = 100 2006 26.2532922859 2007 24.5301450704 2008 26.8908012031 2009 28.7453415033 2010 32.819830414 2011 32.0675842188 2012 35.3682511215 2013 35.9761737992 2014 39.331980584 2015 48.725885378 2016 47.9400141875 2017 47.3219536384 2018 45.7317350558 2019 48.6031387639 2020 49.3657872982 2021 49.2294559589