Year	US Dollars
1990	13530
1991	14300
1992	14680
1993	14860
1994	15260
1995	16140
1996	16730
1997	17710
1998	18860
1999	19790
2000	21450
2001	22690
2002	24090
2003	24850
2004	25950
2005	27300
2006	30280
2007	31800
2008	32570
2009	31790
2010	31510
2011	31510
2012	31760
2013	32430
2014	33600
2015	34740
2016	36300
2017	37990