Year	US Dollars
1990	8860
1991	9350
1992	10280
1993	10930
1994	10950
1995	10580
1996	11240
1997	12760
1998	13530
1999	13650
2000	13870
2001	14200
2002	13140
2003	13270
2004	14320
2005	16030
2006	17690
2007	18380
2008	17630
2009	17880
2010	18840
2011	20990
2012	21730
2013	23090
2014	23950
2015	24870
2016	26030
2017	26860