Year	current US$
1960	7000000
1961	8000000
1962	7000000
1963	7000000
1964	8000000
1965	9000000
1966	9000000
1967	9000000
1968	9000000
1969	10000000
1970	12000000
1971	15000000
1972	16000000
1973	18000000
1974	19000000
1975	24000000
1976	22000000
1977	22000000
1978	24000000
1979	32000000
1980	45000000
1981	48000000
1982	44000000
1983	51000000
1984	52000000
1985	51000000
1986	63000000
1987	79000000
1988	93000000
1989	102000000
1990	110000000
1991	110000000
1992	95000000
1993	118000000
1994	128000000
1995	133000000
1996	149000000
1997	147000000
1998	149000000
1999	153000000
2000	196000000
2001	189000000
2002	201000000
2003	199000000
2004	183000000
2005	210000000
2006	250000000
2007	272000000
2008	325000000
2009	296000000
2010	270000000
2011	247000000
2012	226000000
2013	249000000
2014	268000000
2015	297000000
2016	333000000
2017	309000000
2018	335000000
2019	338000000
2020	271000000
2021	260000000
2022	326000000
2023	317000000