Year	U.S. dollars (Units)
1980	2462.085
1981	2502.130
1982	2446.588
1983	2514.256
1984	2640.191
1985	2988.545
1986	2929.092
1987	2935.816
1988	2326.571
1989	2309.340
1990	2684.465
1991	1975.201
1992	2033.196
1993	2056.556
1994	1674.567
1995	1626.997
1996	1783.410
1997	1800.196
1998	1772.368
1999	1769.091
2000	1947.755
2001	1919.410
2002	1958.238
2003	2304.603
2004	2839.820
2005	3258.153
2006	3690.572
2007	4208.244
2008	5214.762
2009	4262.144
2010	4941.493
2011	5946.345
2012	6057.974
2013	5997.896
2014	6108.878
2015	4691.686
2016	4426.580
2017	4554.150
2018	4568.244
2019	4452.856
2020	3757.585
2021	4169.984
2022	4981.822
2023	5323.635
2024	5721.678
2025	5869.435
2026	5998.622
2027	6073.858
2028	6129.969
2029	6170.756