Year	US Dollars
1990	11300
1991	12070
1992	11290
1993	11510
1994	12240
1995	12560
1996	12920
1997	13550
1998	14130
1999	12640
2000	11930
2001	12560
2002	12910
2003	12830
2004	12290
2005	13470
2006	12640
2007	13110
2008	12640
2009	12720
2010	13070
2011	13710
2012	14820
2013	15420
2014	16660
2015	16440
2016	16670
2017	17010