Year	US Dollars
1972	2070
1973	2540
1974	2990
1975	3390
1976	3280
1977	3580
1978	4120
1979	5120
1980	6380
1981	6780
1982	6390
1983	5720
1984	5610
1985	5630
1986	6370
1987	8220
1988	10420
1989	11100
1990	12560
1991	13130
1992	14440
1993	14600
1994	15480
1995	16920
1996	18930
1997	20610
1998	21370
1999	22680
2000	24100
2001	24100
2002	24940
2003	29950
2004	37690
2005	44610
2006	48110
2007	50590
2008	51070
2009	46910
2010	44760
2011	43120
2012	41600
2013	44020
2014	46840
2015	51850
2016	53910
2017	55290