Year	U.S. dollars (Units)
1990	1036.534
1991	936.263
1992	748.650
1993	702.439
1994	714.032
1995	717.092
1996	849.876
1997	881.223
1998	1029.202
1999	1003.834
2000	969.824
2001	964.080
2002	922.878
2003	822.472
2004	806.898
2005	764.632
2006	677.881
2007	646.558
2008	553.376
2009	790.352
2010	975.851
2011	1131.675
2012	1310.442
2013	1421.696
2014	1415.278
2015	1425.466
2016	1444.716
2017	1527.052
2018	2531.483
2019	1746.523
2020	1769.564
2021	2324.772
2022	1978.323
2023	1993.038
2024	2087.614
2025	2103.128
2026	2130.658
2027	2156.633
2028	2185.572
2029	2210.142