Year	U.S. dollars (Units)
1980	13449.648
1981	11107.625
1982	10575.644
1983	9671.452
1984	8681.163
1985	8586.407
1986	6733.969
1987	6002.067
1988	5981.627
1989	6070.096
1990	7424.170
1991	8026.293
1992	7950.512
1993	6998.262
1994	6391.134
1995	7102.861
1996	7608.817
1997	7663.003
1998	6171.767
1999	7294.482
2000	7625.010
2001	6693.083
2002	3956.483
2003	4986.326
2004	6180.388
2005	8739.202
2006	10561.373
2007	11801.274
2008	14762.577
2009	10202.806
2010	12478.016
2011	8132.317
2012	14728.067
2013	12025.599
2014	9166.555
2015	7706.743
2016	7817.630
2017	10413.810
2018	11773.943
2019	10532.114
2020	7062.559
2021	5249.501
2022	6387.623
2023	6576.036
2024	6975.330
2025	7241.069
2026	7414.457
2027	7443.760
2028	7479.059
2029	7596.391