Year	U.S. dollars (Units)
1980	10731.955
1981	9280.728
1982	9267.664
1983	9417.235
1984	8882.629
1985	9090.795
1986	12886.095
1987	16093.014
1988	17632.815
1989	17547.811
1990	21827.440
1991	22621.881
1992	25068.398
1993	24152.659
1994	25725.557
1995	30350.529
1996	29820.596
1997	26737.482
1998	27399.085
1999	27210.471
2000	24636.471
2001	24558.922
2002	26508.320
2003	32298.607
2004	36883.892
2005	38450.609
2006	40674.883
2007	46922.558
2008	51914.013
2009	48111.662
2010	46955.173
2011	51452.276
2012	48616.903
2013	50747.384
2014	51814.424
2015	44267.809
2016	45278.829
2017	47320.537
2018	51234.477
2019	50192.490
2020	48837.350
2021	53696.159
2022	52483.930
2023	57081.047
2024	59225.150
2025	61354.469
2026	63303.028
2027	65025.938
2028	66679.531
2029	68360.109