Year	U.S. dollars (Units)
1980	1920.249
1981	2177.087
1982	2448.585
1983	2752.968
1984	3200.985
1985	3763.974
1986	4617.610
1987	5455.264
1988	6547.259
1989	7273.247
1990	7623.434
1991	7927.588
1992	8084.427
1993	8474.038
1994	9097.243
1995	8675.237
1996	9266.473
1997	9678.320
1998	10074.750
1999	10349.520
2000	10931.312
2001	10411.422
2002	10485.776
2003	10921.845
2004	11613.334
2005	12785.872
2006	14317.674
2007	16060.877
2008	16574.257
2009	14688.677
2010	13574.440
2011	13295.364
2012	13825.317
2013	13414.902
2014	13980.610
2015	14728.706
2016	15588.535
2017	15686.747
2018	16889.792
2019	17370.041
2020	14468.071
2021	15709.338
2022	17441.463
2023	19123.213
2024	20532.983
2025	21507.870
2026	22250.512
2027	23019.442
2028	23818.088
2029	24647.694