Year	U.S. dollars (Units)
1990	963.773
1991	1075.877
1992	1268.268
1993	1477.991
1994	1835.045
1995	807.991
1996	396.847
1997	405.612
1998	364.220
1999	427.779
2000	526.881
2001	521.697
2002	551.194
2003	591.218
2004	677.899
2005	796.361
2006	881.275
2007	970.820
2008	1170.964
2009	1061.415
2010	1267.555
2011	1303.586
2012	1369.687
2013	1519.342
2014	1579.558
2015	1508.382
2016	1083.887
2017	905.181
2018	710.384
2019	702.286
2020	633.311
2021	594.166
2022	706.250
2023	540.765
2024	486.382
2025	482.333
2026	540.299
2027	615.081
2028	658.072
2029	690.577