Year maximum value in 2004 = 100 2006 13.6399337931 2007 14.140332408 2008 16.6638040343 2009 18.456800546 2010 19.3061329198 2011 19.517680918 2012 20.454188731 2013 21.7424086546 2014 23.3200273107 2015 29.3661153573 2016 32.1929855536 2017 31.5500723456 2018 31.1068639534 2019 35.456202022 2020 34.3820085567 2021 34.5869279463