Year	U.S. dollars (Units)
1980	706.783
1981	567.856
1982	461.822
1983	425.523
1984	377.995
1985	383.932
1986	521.836
1987	594.487
1988	641.990
1989	611.524
1990	715.236
1991	686.607
1992	699.731
1993	536.718
1994	414.629
1995	523.522
1996	550.724
1997	542.959
1998	499.320
1999	486.879
2000	402.180
2001	388.651
2002	435.683
2003	526.449
2004	547.700
2005	539.198
2006	540.082
2007	621.808
2008	735.775
2009	737.152
2010	722.819
2011	803.341
2012	782.049
2013	847.400
2014	877.419
2015	770.221
2016	792.222
2017	813.108
2018	873.964
2019	848.341
2020	876.511
2021	964.325
2022	919.575
2023	998.245
2024	1058.319
2025	1109.584
2026	1163.317
2027	1220.298
2028	1280.209
2029	1343.708