Year	U.S. dollars (Units)
1980	11109.741
1981	9329.591
1982	9014.978
1983	9025.206
1984	8537.765
1985	8678.853
1986	12387.010
1987	15411.529
1988	16514.654
1989	16232.121
1990	20249.138
1991	23453.063
1992	26538.126
1993	25602.881
1994	27233.717
1995	31829.610
1996	30664.393
1997	27170.747
1998	27528.158
1999	26984.243
2000	23924.876
2001	23869.773
2002	25460.334
2003	30668.849
2004	34534.814
2005	35020.197
2006	36894.468
2007	42299.862
2008	46367.716
2009	42338.844
2010	42379.710
2011	46697.376
2012	43883.393
2013	46299.227
2014	48035.950
2015	41107.096
2016	42124.196
2017	44636.833
2018	47961.181
2019	46810.283
2020	46711.984
2021	51460.987
2022	48756.309
2023	52726.965
2024	54290.944
2025	56438.537
2026	58471.507
2027	60264.387
2028	61964.994
2029	63550.744