Year	U.S. dollars (Units)
1980	447.907
1981	484.330
1982	494.856
1983	521.763
1984	567.915
1985	619.461
1986	676.077
1987	327.179
1988	212.610
1989	192.614
1990	240.230
1991	211.528
1992	124.533
1993	147.025
1994	397.214
1995	618.383
1996	626.299
1997	706.797
1998	773.837
1999	847.945
2000	794.059
2001	720.822
2002	684.333
2003	540.556
2004	660.218
2005	773.350
2006	794.790
2007	991.684
2008	1074.359
2009	1168.747
2010	1175.199
2011	1269.346
2012	1316.496
2013	1408.807
2014	1408.669
2015	1359.209
2016	1263.434
2017	1337.160
2018	1441.864
2019	1277.213
2020	1235.476
2021	1765.242
2022	1643.221
2023	1761.086
2024	1940.632
2025	1939.887
2026	1902.835
2027	1873.309
2028	1881.008
2029	1915.761