Year	U.S. dollars (Units)
1980	2133.685
1981	2113.068
1982	1876.637
1983	1753.332
1984	1668.464
1985	1835.181
1986	1983.050
1987	2260.660
1988	2333.225
1989	2707.896
1990	3738.161
1991	3691.370
1992	3818.769
1993	4261.644
1994	3026.717
1995	3880.859
1996	4099.228
1997	4221.923
1998	4384.471
1999	4020.272
2000	4237.961
2001	3082.899
2002	3617.230
2003	4684.698
2004	6015.665
2005	7350.887
2006	7961.078
2007	9640.571
2008	10778.131
2009	8941.404
2010	10533.450
2011	11221.402
2012	11637.915
2013	12488.968
2014	12079.287
2015	10973.586
2016	10891.190
2017	10628.898
2018	9514.047
2019	9145.817
2020	8612.903
2021	9663.877
2022	10621.965
2023	12849.000
2024	12764.707
2025	12551.425
2026	12942.701
2027	13298.255
2028	13656.204
2029	14010.767