Year	U.S. dollars (Units)
1980	4671.078
1981	5085.580
1982	5041.589
1983	4883.234
1984	3447.450
1985	3472.186
1986	3488.564
1987	2619.240
1988	3292.792
1989	2378.158
1990	2492.939
1991	2685.293
1992	2968.496
1993	2876.077
1994	2741.979
1995	3559.770
1996	3174.631
1997	3778.537
1998	3970.433
1999	4133.370
2000	4820.646
2001	4963.916
2002	3778.255
2003	3266.095
2004	4311.999
2005	5421.656
2006	6646.803
2007	8538.102
2008	11079.069
2009	9557.550
2010	11158.180
2011	10934.275
2012	12688.110
2013	8692.955
2014	7107.443
2015	4096.971
2016	3676.384
2017	3806.656
2018	3529.720
2019	2624.411
2020	1566.602
2021	2090.398
2022	3421.754
2023	3659.195
2024	3867.439
2025	3968.917