Year	U.S. dollars (Units)
1980	1070.284
1981	1140.215
1982	1126.186
1983	1139.957
1984	1163.059
1985	1338.718
1986	705.755
1987	796.957
1988	841.769
1989	946.757
1990	813.346
1991	967.343
1992	1044.285
1993	1111.333
1994	1227.018
1995	1349.852
1996	1408.114
1997	1559.741
1998	1658.175
1999	1529.954
2000	1555.567
2001	1654.953
2002	1795.772
2003	1847.291
2004	1951.798
2005	2151.742
2006	2336.955
2007	2556.760
2008	2873.086
2009	2654.100
2010	2836.060
2011	3172.124
2012	3267.792
2013	3397.625
2014	3632.101
2015	3825.882
2016	3982.020
2017	4234.379
2018	4251.613
2019	4388.497
2020	4337.784
2021	4708.382
2022	5097.593
2023	5368.885
2024	5678.085
2025	5971.242
2026	6283.336
2027	6615.301
2028	6972.299
2029	7348.849