Year	U.S. dollars (Units)
1980	705.484
1981	744.913
1982	767.410
1983	824.445
1984	845.080
1985	772.393
1986	840.315
1987	967.712
1988	1160.538
1989	1338.257
1990	1564.175
1991	1769.043
1992	1999.204
1993	2209.362
1994	2491.433
1995	2846.590
1996	3043.982
1997	2468.182
1998	1845.829
1999	2033.260
2000	2007.735
2001	1893.264
2002	2096.189
2003	2359.116
2004	2660.126
2005	2894.060
2006	3369.545
2007	3973.019
2008	4379.659
2009	4213.010
2010	5076.339
2011	5492.115
2012	5860.583
2013	6168.268
2014	5951.877
2015	5840.050
2016	5993.308
2017	6593.816
2018	7298.941
2019	7812.886
2020	7169.943
2021	7237.318
2022	7072.755
2023	7337.194
2024	7811.598
2025	8153.025
2026	8608.040
2027	9146.988
2028	9639.942
2029	10091.390