Year	US Dollars
1962	820
1963	900
1964	960
1965	1060
1966	1160
1967	1240
1968	1370
1969	1560
1970	1750
1971	1910
1972	2100
1973	2380
1974	2590
1975	2660
1976	2650
1977	2740
1978	2980
1979	3390
1980	3720
1981	3890
1982	3770
1983	3670
1984	3970
1985	4280
1986	4750
1987	5350
1988	5860
1989	6050
1990	5950
1991	6300
1992	6760
1993	7100
1994	7370
1995	7820
1996	8130
1997	8510
1998	8690
1999	9590
2000	10550
2001	10950
2002	11250
2003	12170
2004	14260
2005	14750
2006	15030
2007	15860
2008	16360
2009	16580
2010	16920
2011	17670
2012	18680
2013	19170
2014	19280
2015	19430
2016	19460