Year	U.S. dollars (Units)
1994	1227.237
1995	1322.057
1996	1296.081
1997	1350.947
1998	1416.578
1999	1441.889
2000	1412.750
2001	1275.685
2002	1102.500
2003	1197.161
2004	1350.906
2005	1461.093
2006	1480.704
2007	1563.701
2008	1913.316
2009	2061.558
2010	2406.261
2011	2711.917
2012	2888.598
2013	3122.985
2014	3158.599
2015	3084.132
2016	3325.846
2017	3407.307
2018	3353.225
2019	3442.754
2020	3044.744
2021	3464.383
2022	3579.222
2023	3396.263