Year	U.S. dollars (Units)
1980	2108.750
1981	1111.350
1982	1071.935
1983	1257.355
1984	1421.164
1985	1478.366
1986	1611.323
1987	1612.564
1988	1598.038
1989	1763.481
1990	1880.750
1991	2305.412
1992	2684.089
1993	2926.912
1994	3110.155
1995	3336.709
1996	3277.614
1997	3450.907
1998	3653.154
1999	3715.408
2000	3941.140
2001	4041.943
2002	4122.829
2003	4227.819
2004	4483.590
2005	4756.337
2006	5309.271
2007	6194.045
2008	6993.896
2009	6879.266
2010	8268.859
2011	9270.571
2012	10107.452
2013	10764.529
2014	10853.638
2015	11635.197
2016	11986.918
2017	12185.259
2018	12428.924
2019	12691.126
2020	12163.927
2021	12539.282
2022	13239.876
2023	16390.222
2024	18030.977
2025	19031.469
2026	19903.189
2027	20864.865
2028	21876.331
2029	22912.308