Year	US Dollars
1990	9540
1991	10340
1992	10600
1993	11380
1994	12060
1995	11450
1996	12170
1997	12820
1998	13260
1999	13600
2000	14180
2001	13870
2002	13740
2003	14780
2004	15820
2005	17320
2006	19910
2007	22070
2008	22130
2009	19430
2010	18310
2011	17960
2012	18580
2013	18980
2014	20040
2015	20970
2016	22090
2017	22980