Year	U.S. dollars (Units)
1980	13886.370
1981	12076.174
1982	11801.273
1983	11852.891
1984	11561.767
1985	12259.279
1986	17215.426
1987	21349.948
1988	22528.114
1989	21913.155
1990	26920.581
1991	27052.653
1992	29622.474
1993	27640.496
1994	30050.878
1995	35471.255
1996	35732.689
1997	32897.570
1998	33426.974
1999	33492.354
2000	30798.717
2001	30806.607
2002	33275.556
2003	40512.045
2004	46571.283
2005	48872.095
2006	52121.249
2007	58641.193
2008	64531.119
2009	58286.537
2010	58177.162
2011	61864.093
2012	58623.414
2013	61325.575
2014	62729.499
2015	53478.495
2016	54862.848
2017	57772.553
2018	61724.492
2019	59678.596
2020	60926.877
2021	69466.552
2022	68131.892
2023	68299.821
2024	68897.547
2025	71127.031
2026	73789.087
2027	76475.599
2028	79283.332
2029	82204.806