Year maximum value in 2004 = 100 2006 33.9874764462 2007 26.8606126171 2008 31.2446601341 2009 30.1273137487 2010 30.3791297012 2011 41.4960890933 2012 42.354922725 2013 46.4782300208 2014 46.2184395607 2015 46.3957480403 2016 47.5173120519 2017 50.9806406975 2018 49.1925303635 2019 48.9645093684 2020 48.3523875611 2021 48.1822269776