Year	U.S. dollars (Units)
1980	2052.081
1981	2450.352
1982	2441.211
1983	2125.157
1984	1710.302
1985	2101.997
1986	2264.368
1987	2517.949
1988	2593.057
1989	2314.744
1990	1641.855
1991	1241.063
1992	847.680
1993	1147.325
1994	1317.048
1995	1563.117
1996	1565.472
1997	1571.689
1998	1885.349
1999	1600.881
2000	1667.613
2001	1800.966
2002	2108.445
2003	2672.061
2004	3487.699
2005	4608.801
2006	5744.634
2007	8273.885
2008	10446.484
2009	8540.187
2010	8391.048
2011	9546.749
2012	8919.363
2013	9481.981
2014	10025.457
2015	8951.736
2016	9378.957
2017	10717.263
2018	12465.699
2019	12928.148
2020	13021.962
2021	14895.318
2022	15821.133
2023	18175.989
2024	19529.841
2025	20693.270
2026	22083.359
2027	23598.490
2028	25114.876
2029	26635.981