Year % of GDP 2001 12.987611817898573 2002 15.002317139219501 2003 15.741119708106426 2004 15.71887681804218 2005 16.825899462506865 2006 19.65470095101357 2007 21.678718240213048 2008 21.130276181282337 2009 24.528079119919525 2010 25.261427799990667 2011 26.772502490938876 2012 28.46313493010408 2013 31.705885549756402 2014 32.50040675844178 2015 35.23812263065374 2016 37.28661605194581 2017 38.215498613867744 2018 37.32449971443263 2019 39.19793493807317 2020 40.79915316519873 2021 38.86001201965763 2022 37.86385693456063 2023 36.6188425068002