Year	US Dollars
1962	1220
1963	1310
1964	1460
1965	1700
1966	1840
1967	2000
1968	2230
1969	2480
1970	2790
1971	3170
1972	3800
1973	5000
1974	6280
1975	7520
1976	8220
1977	8960
1978	10300
1979	12570
1980	14600
1981	13790
1982	12160
1983	10900
1984	10570
1985	10180
1986	11520
1987	14500
1988	18290
1989	19240
1990	20010
1991	20960
1992	23170
1993	23680
1994	24990
1995	27270
1996	29330
1997	29380
1998	27830
1999	28270
2000	28460
2001	27020
2002	26640
2003	30540
2004	37100
2005	41950
2006	45850
2007	49090
2008	52460
2009	53520
2010	53530
2011	54120
2012	52500
2013	52330
2014	51330
2015	49030
2016	46610
2017	46180