Year	U.S. dollars (Units)
1980	19543.400
1981	20846.234
1982	16507.688
1983	13252.612
1984	11687.983
1985	9666.717
1986	7698.924
1987	7221.944
1988	7083.156
1989	7287.351
1990	8562.256
1991	9143.216
1992	9242.614
1993	8740.690
1994	8663.638
1995	8957.462
1996	9666.916
1997	9858.952
1998	8512.488
1999	9144.561
2000	10448.532
2001	9898.261
2002	9937.388
2003	11027.901
2004	12891.306
2005	15943.392
2006	17827.359
2007	19196.033
2008	23403.614
2009	18836.932
2010	22028.346
2011	26966.315
2012	28348.593
2013	27290.198
2014	27079.664
2015	22453.563
2016	21515.651
2017	23081.196
2018	28036.044
2019	27892.807
2020	23271.404
2021	28396.086
2022	34454.212
2023	32529.702
2024	33039.932
2025	34295.407
2026	35285.513
2027	36302.672
2028	37238.233
2029	38672.433