Year	U.S. dollars (Units)
1980	13069.505
1981	11456.040
1982	10822.037
1983	10292.761
1984	9697.432
1985	10108.561
1986	13947.316
1987	16793.955
1988	18240.997
1989	18236.767
1990	22490.289
1991	22406.387
1992	24590.746
1993	23082.715
1994	24262.184
1995	27741.294
1996	27720.861
1997	25028.466
1998	25818.370
1999	25550.782
2000	23212.450
2001	23245.258
2002	25137.402
2003	30682.636
2004	35016.219
2005	36057.117
2006	37795.916
2007	43060.031
2008	47155.211
2009	43190.972
2010	42178.577
2011	45419.973
2012	42372.071
2013	44144.638
2014	44616.455
2015	37937.861
2016	38348.507
2017	40134.128
2018	43060.590
2019	41924.837
2020	40529.093
2021	45161.226
2022	42306.085
2023	46000.803
2024	47358.557
2025	48631.151
2026	50143.044
2027	51571.118
2028	53040.148
2029	54388.208