Year	U.S. dollars (Units)
1980	1219.569
1981	1057.067
1982	1075.452
1983	1145.987
1984	1097.548
1985	985.391
1986	1288.644
1987	1947.606
1988	2439.381
1989	2628.077
1990	2797.478
1991	2718.950
1992	2729.751
1993	2674.397
1994	2802.477
1995	3084.800
1996	3087.859
1997	3071.641
1998	2886.260
1999	3188.541
2000	3290.347
2001	3099.104
2002	3005.538
2003	4088.461
2004	4743.633
2005	5194.705
2006	5142.914
2007	5371.808
2008	5345.848
2009	4938.250
2010	6041.732
2011	7080.778
2012	6392.987
2013	6436.603
2014	6844.033
2015	5869.738
2016	6411.552
2017	6705.341
2018	6947.818
2019	6679.188
2020	5863.182
2021	7238.796
2022	7737.655
2023	7642.011
2024	7875.313
2025	8243.376
2026	8847.123
2027	9404.977
2028	10001.764
2029	10637.143