Year	US Dollars
1997	22.23461
1998	13.55261
1999	36.59974
2000	41.93638
2001	40.86171
2002	49.11065
2003	41.00995
2004	41.40161
2005	58.74382
2006	78.0363
2007	94.04032
2008	103.93425
2009	85.78071
2010	165.2521
2011	161.39063
2012	166.23641
2013	121.93843
2014	181.18737
2015	110.21947
2016	93.48291
2017	88.27344
2018	95.93666
2019	128.19493
2020	198.8365
2021	229.44676