Year	current US$
2000	13.36023426
2001	13.97040335
2002	16.62016637
2003	22.07415693
2004	26.78050906
2005	18.42695028
2006	18.68846101
2007	22.96313823
2008	26.86379933
2009	28.78603052
2010	30.49008992
2011	35.22418167
2012	35.35765622
2013	38.98682148
2014	35.46997649
2015	31.09540412
2016	31.61802137
2017	33.0976817
2018	35.75557619
2019	37.6062267
2020	38.21287068
2021	39.72068652