Year	U.S. dollars (Units)
1980	1534.317
1981	1677.447
1982	1545.099
1983	1562.130
1984	2397.598
1985	1022.611
1986	1212.354
1987	1245.272
1988	1113.835
1989	1230.744
1990	1123.244
1991	1365.232
1992	1573.686
1993	1741.669
1994	1916.439
1995	2141.061
1996	2309.916
1997	2495.032
1998	2658.543
1999	2674.828
2000	2894.303
2001	3007.381
2002	3158.393
2003	2460.554
2004	2540.849
2005	4008.356
2006	4188.715
2007	4803.473
2008	5194.799
2009	5151.172
2010	5688.751
2011	6063.350
2012	6274.865
2013	6413.934
2014	6805.662
2015	7139.507
2016	7521.268
2017	7874.941
2018	8340.961
2019	8595.180
2020	7553.509
2021	8962.314
2022	10711.156
2023	11186.956
2024	11773.566
2025	12491.628
2026	13259.277
2027	14094.600
2028	14985.791
2029	15925.300