Year	U.S. dollars (Units)
1980	664.574
1981	1044.130
1982	703.042
1983	779.820
1984	581.032
1985	514.181
1986	494.509
1987	768.935
1988	767.651
1989	599.952
1990	472.193
1991	238.480
1992	216.036
1993	247.107
1994	346.255
1995	401.893
1996	401.413
1997	423.918
1998	402.455
1999	370.515
2000	355.466
2001	347.812
2002	361.953
2003	361.772
2004	430.758
2005	483.032
2006	527.739
2007	634.361
2008	784.496
2009	815.808
2010	808.713
2011	872.039
2012	950.574
2013	964.833
2014	1008.018
2015	848.690
2016	828.167
2017	838.495
2018	879.044
2019	951.517
2020	919.434
2021	1006.739
2022	1082.310
2023	1139.300
2024	1201.968
2025	1286.035
2026	1350.667
2027	1411.364
2028	1491.849
2029	1612.488