Year	U.S. dollars (Units)
1980	567.517
1981	591.496
1982	527.416
1983	510.503
1984	555.734
1985	410.217
1986	398.258
1987	440.578
1988	558.144
1989	534.576
1990	505.422
1991	562.267
1992	827.265
1993	781.484
1994	876.462
1995	883.582
1996	1031.874
1997	1001.068
1998	918.686
1999	930.929
2000	890.425
2001	755.273
2002	853.916
2003	1082.547
2004	1147.277
2005	1231.148
2006	1188.669
2007	1432.089
2008	1518.603
2009	1410.095
2010	1609.343
2011	1877.755
2012	1956.664
2013	1886.873
2014	1845.476
2015	1742.421
2016	1845.780
2017	1959.950
2018	2022.227
2019	1847.108
2020	1874.170
2021	2385.414
2022	2199.422
2023	2231.448
2024	2446.127
2025	2569.127
2026	2662.894
2027	2736.923
2028	2801.082
2029	2868.917