Year	current US$
2000	16.94667510369224
2001	16.23032841559903
2002	17.188240584088614
2003	19.709494111355344
2004	22.515534365246708
2005	25.619877201630498
2006	29.60746400527324
2007	34.20684783622451
2008	38.64574489004076
2009	39.189550571685736
2010	40.57342120468409
2011	44.533163964809006
2012	45.1833117366357
2013	49.03674640950242
2014	49.49281274034875
2015	46.92787670033478
2016	46.38486488817582
2017	45.949845354060095
2018	45.76656655075067
2019	47.044276345917055
2020	48.01280141300587
2021	51.86479739716377