Year	current US$
1960	2000000
1961	1000000
1962	1000000
1963	1000000
1964	1000000
1965	2000000
1966	2000000
1967	2000000
1968	3000000
1969	3000000
1970	2000000
1971	2000000
1972	3000000
1973	4000000
1974	7000000
1975	6000000
1976	9000000
1977	11000000
1978	15000000
1979	22000000
1980	21000000
1981	17000000
1982	15000000
1983	20000000
1984	26000000
1985	28000000
1986	18000000
1987	22000000
1988	32000000
1989	34000000
1990	56000000
1991	49000000
1992	48000000
1993	51000000
1994	51000000
1995	52000000
1996	140000000
1997	113000000
1998	122000000
1999	145000000
2000	194000000
2001	216000000
2002	228000000
2003	274000000
2004	291000000
2005	340000000
2006	380000000
2007	360000000
2008	430000000
2009	395000000
2010	400000000
2011	483000000
2012	497000000
2013	578000000
2014	540000000
2015	415000000
2016	460000000
2017	547000000
2018	569000000
2019	518000000
2020	432000000
2021	464000000
2022	537000000
2023	541000000