Year	constant 2015 US$
1973	40000
1974	14290000
1975	8070000
1976	11070000
1977	17080000
1978	10620000
1979	8490000
1980	12140000
1981	19750000
1982	10990000
1983	7610000
1984	5350000
1985	6370000
1986	9880000
1987	10000000
1988	13830000
1989	6710000
1990	6410000
1991	9470000
1992	6200000
1993	4200000
1994	5540000
1995	2710000
1996	4660000
1997	5470000
1998	11990000
1999	11460000
2000	12690000
2001	10720000
2002	15640000
2003	6140000
2004	1840000
2005	8100000
2006	3330000
2007	4530000
2008	5160000
2009	3870000
2010	17060000
2011	12090000
2012	1790000
2013	1430000
2014	2300000
2015	1660000
2016	60000
2017	9800000