Year	current US$
2000	13.1751833
2001	13.99944115
2002	14.81900692
2003	18.62379265
2004	21.77468681
2005	20.60617447
2006	22.31639481
2007	18.39959717
2008	19.69238472
2009	22.65766335
2010	24.43300056
2011	33.27035522
2012	25.96233749
2013	29.52669525
2014	31.54170799
2015	26.82466125
2016	23.64590836
2017	22.35861588
2018	24.02440262
2019	25.98394394
2020	24.70353127
2021	25.36040497