Year	current US$
1960	7000000
1961	6000000
1962	6000000
1963	6000000
1964	6000000
1965	5000000
1966	6000000
1967	8000000
1968	9000000
1969	9000000
1970	8000000
1971	7000000
1972	7000000
1973	13000000
1974	17000000
1975	7000000
1976	8000000
1977	23000000
1978	21000000
1979	27000000
1980	16000000
1981	8000000
1982	12000000
1983	5000000
1984	9000000
1985	6000000
1986	9000000
1987	4000000
1988	4000000
1989	6000000
1990	4000000
1991	6000000
1992	5000000
1993	5000000
1994	8000000
1995	5000000
1996	4000000
1997	5000000
1998	5000000
1999	2000000
2000	3000000
2001	3000000
2002	5000000
2003	7000000
2004	5000000
2005	7000000
2006	8000000
2007	7000000
2008	11000000
2009	8000000
2010	11000000
2011	11000000
2012	12000000
2013	13000000
2014	17000000
2015	11000000
2016	14000000
2017	16000000
2018	16000000
2019	13000000
2020	14000000
2021	21000000
2022	22000000
2023	20000000