Year	current US$
2000	16.41194344
2001	15.98436737
2002	15.7368412
2003	14.2323103
2004	18.61294365
2005	25.88375473
2006	31.62604523
2007	36.13018799
2008	40.08214951
2009	44.42161942
2010	51.96447372
2011	55.3051796
2012	55.14218903
2013	53.0015564
2014	51.04053879
2015	40.15630341
2016	39.13254166
2017	31.47759247
2018	32.99159622
2019	33.40487289
2020	36.87842941
2021	43.44807434