Year	US Dollars
1962	1370
1963	1470
1964	1620
1965	1810
1966	1970
1967	2060
1968	2090
1969	2270
1970	2470
1971	2690
1972	3170
1973	4030
1974	5130
1975	6320
1976	6840
1977	7190
1978	7910
1979	9540
1980	11450
1981	11980
1982	11700
1983	10840
1984	10790
1985	11130
1986	13010
1987	16480
1988	21540
1989	24110
1990	26000
1991	25090
1992	24170
1993	20680
1994	20170
1995	22030
1996	24970
1997	26650
1998	25790
1999	26040
2000	26420
2001	25780
2002	25510
2003	28680
2004	35200
2005	40100
2006	42740
2007	46040
2008	49920
2009	48590
2010	49330
2011	49910
2012	48670
2013	49220
2014	48990
2015	46630
2016	45040
2017	44580