Year	U.S. dollars (Units)
1980	903.445
1981	1110.425
1982	1227.421
1983	1309.102
1984	1435.282
1985	1537.223
1986	1686.100
1987	1828.411
1988	2077.695
1989	2211.424
1990	2456.285
1991	2584.104
1992	2815.081
1993	2896.038
1994	2924.036
1995	3188.478
1996	3340.515
1997	3500.225
1998	3755.704
1999	3922.719
2000	3973.449
2001	4284.994
2002	4518.089
2003	4710.272
2004	5082.069
2005	5353.688
2006	5933.621
2007	6572.506
2008	6740.480
2009	6564.113
2010	6613.132
2011	6544.688
2012	6686.015
2013	6988.344
2014	7028.297
2015	7154.784
2016	7390.469
2017	7643.104
2018	8001.555
2019	8234.203
2020	7851.359
2021	7873.226
2022	8538.685
2023	9377.364
2024	10150.323
2025	10745.206
2026	11254.526
2027	11776.520
2028	12322.725
2029	12894.264