Year	U.S. dollars (Units)
1980	1268.332
1981	1008.636
1982	853.044
1983	752.384
1984	671.076
1985	667.569
1986	885.759
1987	1043.902
1988	1077.321
1989	1071.039
1990	1219.584
1991	1237.554
1992	1301.275
1993	1157.837
1994	774.866
1995	896.009
1996	1008.344
1997	893.112
1998	762.522
1999	877.222
2000	1156.361
2001	933.558
2002	999.604
2003	1128.049
2004	1439.638
2005	1811.590
2006	2116.981
2007	2220.174
2008	2848.341
2009	2281.470
2010	2965.182
2011	3414.461
2012	3756.238
2013	3719.705
2014	3623.464
2015	2348.056
2016	2106.937
2017	2226.946
2018	2716.492
2019	2509.047
2020	2014.193
2021	2293.987
2022	2338.415
2023	2349.952
2024	2456.868
2025	2502.076
2026	2562.217
2027	2637.094
2028	2723.138
2029	2833.752