Year	U.S. dollars (Units)
1980	774.484
1981	829.816
1982	843.471
1983	735.714
1984	678.342
1985	645.597
1986	615.047
1987	666.915
1988	744.307
1989	816.961
1990	828.821
1991	830.407
1992	946.762
1993	949.733
1994	1094.543
1995	1237.311
1996	1316.406
1997	1279.835
1998	988.487
1999	1112.353
2000	1087.287
2001	1003.957
2002	1050.297
2003	1062.619
2004	1137.068
2005	1261.241
2006	1470.825
2007	1764.683
2008	2011.634
2009	1923.674
2010	2237.157
2011	2473.249
2012	2721.252
2013	2903.189
2014	2995.504
2015	3039.234
2016	3107.646
2017	3153.314
2018	3279.519
2019	3512.195
2020	3325.836
2021	3576.110
2022	3623.593
2023	3867.672
2024	4130.275
2025	4414.976
2026	4730.267
2027	5065.527
2028	5463.058
2029	5895.856