Year	U.S. dollars (Units)
1980	6093.615
1981	5376.616
1982	4930.527
1983	4619.015
1984	4346.388
1985	4478.468
1986	5735.355
1987	4245.955
1988	4581.144
1989	4899.234
1990	6815.634
1991	5993.320
1992	6015.511
1993	5677.618
1994	4293.942
1995	4956.842
1996	5552.917
1997	5068.093
1998	4161.617
1999	4222.734
2000	4477.321
2001	4065.933
2002	4210.284
2003	5015.596
2004	5837.617
2005	6942.698
2006	7271.093
2007	8652.145
2008	10418.276
2009	7856.853
2010	8933.306
2011	10893.464
2012	9903.410
2013	9760.747
2014	9746.786
2015	7453.114
2016	7082.218
2017	7370.349
2018	8198.560
2019	8086.528
2020	7276.301
2021	9476.107
2022	9751.999
2023	9289.891
2024	9307.875
2025	9148.378
2026	9094.964
2027	9072.123
2028	9093.172
2029	9105.323