Year	U.S. dollars (Units)
1980	3074.684
1981	3122.686
1982	2806.158
1983	3062.892
1984	2633.905
1985	1955.165
1986	2176.064
1987	2801.310
1988	2954.825
1989	3004.440
1990	3425.585
1991	3587.879
1992	3802.578
1993	3716.193
1994	3786.210
1995	4145.210
1996	3869.700
1997	3937.658
1998	3508.140
1999	3423.595
2000	3382.066
2001	2964.029
2002	2791.180
2003	4209.220
2004	5415.089
2005	6033.211
2006	6276.173
2007	6776.465
2008	6355.879
2009	6552.265
2010	8130.193
2011	8799.477
2012	8207.059
2013	7458.040
2014	6984.926
2015	6256.667
2016	5750.785
2017	6678.292
2018	6991.709
2019	6622.629
2020	5672.278
2021	6983.509
2022	6684.479
2023	6138.248
2024	5974.912
2025	6067.003
2026	6182.388
2027	6318.676
2028	6444.031
2029	6572.774