Year	U.S. dollars (Units)
1997	2231.747
1998	2242.037
1999	2230.645
2000	2242.869
2001	2422.927
2002	2655.592
2003	2625.241
2004	2634.419
2005	2689.530
2006	2772.864
2007	2893.428
2008	2781.614
2009	2881.209
2010	3029.421
2011	3236.474
2012	3429.278
2013	3584.024
2014	3638.776
2015	3669.497
2016	4121.199
2017	4526.704
2018	4831.380
2019	5246.723
2020	5469.724
2021	5810.239
2022	5786.253
2023	6306.945
2024	6710.545
2025	6943.294
2026	7149.939
2027	7341.455
2028	7538.102
2029	7740.015