Year	U.S. dollars (Units)
1980	2056.073
1981	2062.163
1982	1941.771
1983	1781.084
1984	1828.856
1985	1744.388
1986	1954.085
1987	1776.896
1988	1672.492
1989	1747.117
1990	1959.194
1991	2012.454
1992	2208.958
1993	2339.817
1994	2590.933
1995	2779.973
1996	2975.914
1997	2900.261
1998	2270.075
1999	2638.512
2000	2274.643
2001	2234.467
2002	2463.316
2003	3072.964
2004	3596.695
2005	3940.024
2006	4050.900
2007	4405.164
2008	4553.695
2009	3682.455
2010	4010.982
2011	4802.511
2012	5022.150
2013	5277.410
2014	5622.351
2015	5397.131
2016	5658.236
2017	6049.889
2018	6269.906
2019	6079.485
2020	4920.014
2021	4750.073
2022	5461.977
2023	5992.792
2024	6287.253
2025	6574.521
2026	6897.774
2027	7230.180
2028	7579.424
2029	7936.740