Year	U.S. dollars (Units)
1980	2151.468
1981	2207.127
1982	2249.984
1983	2046.399
1984	1989.904
1985	2022.961
1986	2338.799
1987	2582.848
1988	2838.561
1989	2909.703
1990	3312.337
1991	3350.243
1992	3733.447
1993	3871.071
1994	4170.572
1995	4491.216
1996	4520.761
1997	4591.492
1998	4738.016
1999	4786.245
2000	4619.293
2001	5269.607
2002	6644.610
2003	8409.098
2004	10291.667
2005	11211.246
2006	11483.141
2007	13926.753
2008	15761.631
2009	13066.422
2010	13199.056
2011	14214.126
2012	12969.621
2013	13693.038
2014	14279.016
2015	12700.301
2016	13083.400
2017	14606.266
2018	16421.113
2019	16782.010
2020	16093.626
2021	18712.805
2022	18383.788
2023	22146.885
2024	23318.553
2025	25128.052
2026	26662.066
2027	28304.791
2028	30103.224
2029	31966.095