Year	U.S. dollars (Units)
2004	59313.405
2005	61150.610
2006	64498.508
2007	72991.531
2008	79110.201
2009	67011.543
2010	60426.235
2011	57512.891
2012	50336.185
2013	51986.532
2014	51234.869
2015	43068.693
2016	44308.666
2017	45887.687
2018	49477.281
2019	48043.860
2020	45640.984
2021	54733.239
2022	52541.687
2023	57259.300
2024	59405.352
2025	60913.271
2026	62676.202
2027	64467.385
2028	66334.868
2029	68186.050
