Year maximum value in 2004 = 100 2006 18.3577227318 2007 17.2485586554 2008 17.4475975059 2009 21.9815154685 2010 25.8010346442 2011 30.2003654591 2012 29.684378672 2013 30.4951239454 2014 30.8695086756 2015 31.7130422124 2016 37.7567804228 2017 37.8635238282 2018 38.3135022682 2019 40.1547594412 2020 39.2007414528 2021 40.4209107384