Year	U.S. dollars (Units)
1980	1714.620
1981	1883.456
1982	1992.290
1983	2198.939
1984	2413.291
1985	2482.400
1986	2834.888
1987	3554.620
1988	4748.676
1989	5817.065
1990	6609.985
1991	7637.199
1992	8126.451
1993	8886.386
1994	10381.180
1995	12565.033
1996	13402.925
1997	12416.754
1998	8271.412
1999	10666.862
2000	12263.471
2001	11563.040
2002	13159.675
2003	14672.418
2004	16482.750
2005	19398.494
2006	21730.952
2007	24083.338
2008	21387.709
2009	19139.732
2010	23077.161
2011	25100.188
2012	25459.168
2013	27179.519
2014	29252.933
2015	28737.439
2016	29274.232
2017	31600.735
2018	33447.155
2019	31902.415
2020	31728.306
2021	35125.524
2022	32394.683
2023	33192.046
2024	34164.985
2025	35785.088
2026	37408.841
2027	39011.544
2028	40654.953
2029	42326.204