Year	U.S. dollars (Units)
1980	16877.243
1981	15396.745
1982	13576.621
1983	12470.948
1984	12976.142
1985	13549.507
1986	17852.720
1987	21629.289
1988	24339.270
1989	25412.176
1990	30253.863
1991	31490.221
1992	32584.883
1993	24351.052
1994	25978.285
1995	30246.923
1996	32986.123
1997	30307.156
1998	30585.081
1999	30928.571
2000	29589.141
2001	27207.490
2002	29846.186
2003	37249.257
2004	42736.876
2005	43349.851
2006	46425.841
2007	53496.534
2008	55929.862
2009	46734.909
2010	52658.794
2011	60540.218
2012	57816.023
2013	60845.007
2014	59704.814
2015	51274.278
2016	51590.473
2017	53459.072
2018	54295.731
2019	51694.498
2020	52706.294
2021	61203.119
2022	56114.285
2023	56224.808
2024	58528.523
2025	60672.785
2026	62869.958
2027	65252.047
2028	67648.900
2029	70143.702