Year	US Dollars
1990	6680
1991	7780
1992	8890
1993	9570
1994	10190
1995	9950
1996	10540
1997	11440
1998	11830
1999	11460
2000	11500
2001	11090
2002	9480
2003	10530
2004	11720
2005	13290
2006	14730
2007	16430
2008	17270
2009	16110
2010	17710
2011	19070
2012	19120
2013	19730
2014	19400
2015	19630
2016	19260
2017	20270