Year	current US$
1960	7000000
1961	5000000
1962	8000000
1963	7000000
1964	7000000
1965	6000000
1966	5000000
1967	4000000
1968	5000000
1969	6000000
1970	5000000
1971	6000000
1972	5000000
1973	7000000
1974	13000000
1975	7000000
1976	7000000
1977	15000000
1978	11000000
1979	18000000
1980	17000000
1981	11000000
1982	13000000
1983	18000000
1984	20000000
1985	16000000
1986	11000000
1987	12000000
1988	15000000
1989	13000000
1990	9000000
1991	6000000
1992	6000000
1993	6000000
1994	4000000
1995	9000000
1996	10000000
1997	15000000
1998	15000000
1999	20000000
2000	65000000
2001	63000000
2002	71000000
2003	87000000
2004	85000000
2005	87000000
2006	65000000
2007	97000000
2008	72000000
2009	46000000
2010	70000000
2011	66000000
2012	76000000
2013	62000000
2014	51000000
2015	59000000
2016	56000000
2017	44000000
2018	46000000
2019	49000000
2020	37000000
2021	29000000
2022	42000000
2023	42000000