Year	U.S. dollars (Units)
1980	1485.189
1981	1544.093
1982	1514.544
1983	1553.175
1984	1687.191
1985	1628.200
1986	1723.846
1987	1964.493
1988	2275.713
1989	2557.259
1990	2819.969
1991	2981.814
1992	3374.418
1993	3542.791
1994	3555.727
1995	3677.903
1996	3729.822
1997	3675.268
1998	3738.251
1999	3908.248
2000	4333.930
2001	4409.660
2002	4564.499
2003	4704.716
2004	4907.717
2005	5030.684
2006	5442.702
2007	5686.947
2008	5644.950
2009	5336.621
2010	5393.252
2011	5477.024
2012	5573.889
2013	5781.058
2014	5921.368
2015	5958.994
2016	5928.131
2017	5843.870
2018	5791.593
2019	5843.129
2020	4858.609
2021	5636.160
2022	6407.770
2023	6865.047
2024	7170.182
2025	7369.804
2026	7501.171
2027	7634.879
2028	7770.970
2029	7909.488