Year	U.S. dollars (Units)
1980	5357.779
1981	6019.899
1982	6317.029
1983	6148.449
1984	6324.402
1985	7025.700
1986	5214.195
1987	5145.493
1988	5001.098
1989	5278.566
1990	7267.924
1991	6806.242
1992	7213.061
1993	6995.280
1994	7010.595
1995	7284.846
1996	7869.076
1997	7983.970
1998	6920.864
1999	7554.515
2000	9266.358
2001	9088.213
2002	9285.343
2003	9792.637
2004	11042.532
2005	13563.457
2006	15946.355
2007	17716.421
2008	25061.257
2009	19235.875
2010	21677.793
2011	23518.573
2012	24129.012
2013	23328.489
2014	23219.693
2015	18924.970
2016	17020.387
2017	17731.849
2018	19885.103
2019	19069.311
2020	17076.319
2021	19652.020
2022	23446.795
2023	21623.401
2024	20913.300
2025	20660.139
2026	20697.247
2027	20809.678
2028	21005.500
2029	20916.436