Year	US Dollars
1990	14250
1991	13580
1992	13950
1993	14810
1994	15930
1995	16780
1996	17090
1997	17990
1998	18440
1999	19350
2000	20290
2001	21380
2002	22130
2003	22830
2004	23670
2005	24020
2006	25900
2007	27290
2008	27700
2009	29440
2010	29710
2011	31250
2012	31610
2013	34740
2014	35730
2015	36090
2016	37190
2017	39740