Year	US Dollars
1962	2340
1963	2360
1964	2470
1965	2670
1966	2920
1967	3080
1968	3370
1969	3680
1970	3970
1971	4390
1972	5050
1973	6060
1974	7190
1975	7990
1976	8690
1977	9040
1978	9700
1979	10550
1980	11530
1981	12300
1982	11810
1983	12100
1984	13050
1985	13830
1986	14450
1987	16200
1988	18480
1989	19710
1990	20480
1991	20800
1992	21220
1993	21080
1994	20740
1995	20740
1996	20700
1997	21200
1998	20760
1999	21300
2000	22610
2001	22980
2002	23490
2003	25360
2004	29370
2005	34120
2006	37780
2007	41420
2008	44810
2009	43110
2010	44370
2011	47060
2012	50900
2013	52620
2014	51930
2015	47460
2016	43880
2017	42870