Year	U.S. dollars (Units)
1980	292.782
1981	320.559
1982	329.641
1983	339.297
1984	317.361
1985	364.611
1986	399.283
1987	428.416
1988	442.811
1989	447.143
1990	417.717
1991	298.957
1992	317.043
1993	325.858
1994	223.451
1995	245.276
1996	268.930
1997	345.662
1998	338.306
1999	284.166
2000	266.055
2001	248.990
2002	242.338
2003	257.700
2004	277.634
2005	334.407
2006	368.508
2007	442.334
2008	545.574
2009	585.040
2010	612.395
2011	674.982
2012	730.185
2013	728.395
2014	749.269
2015	758.834
2016	753.876
2017	783.521
2018	797.104
2019	836.016
2020	803.372
2021	853.124
2022	1004.718
2023	1038.642
2024	988.740
2025	998.040
2026	1049.035
2027	1107.422
2028	1182.635
2029	1271.273