Year	U.S. dollars (Units)
1980	614.040
1981	401.430
1982	385.574
1983	330.580
1984	341.857
1985	359.165
1986	448.478
1987	519.040
1988	527.911
1989	476.325
1990	562.898
1991	558.099
1992	601.645
1993	560.707
1994	375.963
1995	495.048
1996	524.067
1997	489.136
1998	510.571
1999	542.240
2000	503.220
2001	508.351
2002	563.980
2003	698.234
2004	783.763
2005	806.350
2006	837.176
2007	944.755
2008	1098.826
2009	1060.566
2010	1010.314
2011	1099.221
2012	1113.274
2013	1214.313
2014	1251.827
2015	1041.758
2016	1049.531
2017	1094.888
2018	1194.023
2019	1171.015
2020	1239.740
2021	1361.816
2022	1304.748
2023	1411.222
2024	1512.242
2025	1590.281
2026	1668.555
2027	1752.843
2028	1841.031
2029	1933.517