Year	U.S. dollars (Units)
1980	1773.849
1981	1914.507
1982	1958.735
1983	1969.502
1984	1902.443
1985	1829.115
1986	2237.853
1987	2253.478
1988	2015.788
1989	1292.473
1990	1202.925
1991	1192.601
1992	1397.279
1993	1377.572
1994	1477.449
1995	1516.116
1996	1530.654
1997	1560.985
1998	1685.036
1999	1699.599
2000	1725.576
2001	1795.047
2002	1890.254
2003	1959.792
2004	2127.613
2005	2312.884
2006	2599.815
2007	2773.893
2008	3414.521
2009	3618.892
2010	3914.701
2011	4152.495
2012	4392.657
2013	4483.942
2014	4261.906
2015	4069.994
2016	4009.059
2017	4078.871
2018	4152.265
2019	4165.547
2020	4004.321
2021	4158.625
2022	4317.090
2023	4497.524
2024	4705.339
2025	4942.831
2026	5185.344
2027	5432.157
2028	5686.271
2029	5947.829