Year	U.S. dollars (Units)
1980	584.594
1981	335.220
1982	327.897
1983	584.805
1984	815.211
1985	997.615
1986	678.461
1987	464.657
1988	294.242
1989	353.313
1990	406.199
1991	464.923
1992	517.905
1993	567.210
1994	641.635
1995	727.106
1996	739.317
1997	682.509
1998	254.240
1999	264.926
2000	316.667
2001	318.271
2002	328.928
2003	397.312
2004	459.603
2005	525.985
2006	661.572
2007	787.382
2008	969.073
2009	1032.328
2010	1187.022
2011	1397.003
2012	1566.197
2013	1813.802
2014	1982.523
2015	2124.256
2016	2307.838
2017	2437.127
2018	2551.830
2019	2602.623
2020	2528.997
2021	2495.962
2022	2022.383
2023	2004.349
2024	1976.483
2025	2082.896
2026	2155.759
2027	2247.180
2028	2362.978
2029	2489.503