Year	U.S. dollars (Units)
1980	1053.849
1981	956.137
1982	930.890
1983	931.689
1984	1111.403
1985	976.747
1986	918.675
1987	989.126
1988	1092.048
1989	1054.904
1990	1141.043
1991	1333.385
1992	1357.696
1993	1277.011
1994	1422.849
1995	1479.565
1996	1511.705
1997	1537.620
1998	1441.112
1999	1435.664
2000	1422.228
2001	1317.091
2002	1313.463
2003	1542.059
2004	1743.287
2005	1824.505
2006	1985.275
2007	2308.554
2008	2540.715
2009	2519.625
2010	2719.254
2011	3007.564
2012	2934.853
2013	2940.193
2014	2947.953
2015	2771.657
2016	2844.132
2017	3158.901
2018	3256.353
2019	3187.380
2020	3341.002
2021	2951.692
2022	3219.361
2023	3501.240
2024	3733.740
2025	3919.608
2026	4060.683
2027	4201.470
2028	4326.453
2029	4455.154