Year	U.S. dollars (Units)
1980	227.616
1981	228.061
1982	233.306
1983	251.399
1984	229.991
1985	260.757
1986	262.316
1987	271.537
1988	272.448
1989	277.391
1990	284.636
1991	304.279
1992	310.307
1993	186.665
1994	160.749
1995	151.063
1996	163.498
1997	155.766
1998	137.366
1999	128.578
2000	136.056
2001	131.565
2002	123.874
2003	132.704
2004	152.160
2005	181.490
2006	218.637
2007	266.894
2008	350.570
2009	373.199
2010	341.103
2011	377.694
2012	510.537
2013	548.869
2014	622.592
2015	707.975
2016	790.789
2017	822.704
2018	839.861
2019	948.851
2020	969.014
2021	974.185
2022	1143.024
2023	1511.217
2024	1909.984
2025	2163.217
2026	2394.835
2027	2626.668
2028	2883.624
2029	3171.186