Year	constant 2015 US$
2001	54783.41857033648
2002	51561.449345193425
2003	51946.626651072016
2004	54341.32928674645
2005	54235.05824840401
2006	55268.51763694188
2007	49485.08233856031
2008	44350.94091363404
2009	32360.45833327283
2010	30581.162002038367
2011	35405.96642178451
2012	37843.28271408313
2013	39839.02415360403
2014	41892.18242453835
2015	38036.417301543945
2016	38131.658046674806
2017	40046.30045519799
2018	39029.42336420458
2019	38640.868216265975
2020	34827.347212617045