Year	U.S. dollars (Units)
1980	770.303
1981	850.554
1982	843.209
1983	818.461
1984	854.275
1985	802.926
1986	959.286
1987	1037.126
1988	1213.220
1989	1461.359
1990	1498.504
1991	1750.858
1992	1832.835
1993	1884.492
1994	1948.137
1995	2123.283
1996	2228.293
1997	2263.661
1998	2153.245
1999	1994.282
2000	2045.810
2001	1818.184
2002	1828.634
2003	2015.247
2004	2288.897
2005	2581.930
2006	2865.259
2007	2919.693
2008	3360.507
2009	3040.244
2010	3561.484
2011	4014.770
2012	4581.885
2013	4408.998
2014	4325.614
2015	4319.442
2016	4178.289
2017	4577.988
2018	4784.368
2019	5092.873
2020	4887.486
2021	4695.159
2022	4977.965
2023	5487.667
2024	5840.151
2025	6112.257
2026	6311.946
2027	6515.298
2028	6748.674
2029	6981.651