Year	constant 2015 US$
1975	170000
1976	12980000
1977	9490000
1978	9020000
1979	11080000
1980	10770000
1981	11730000
1982	14330000
1983	10270000
1984	14190000
1985	8920000
1986	10440000
1987	52670000
1988	22600000
1989	10440000
1990	8020000
1991	8070000
1992	11490000
1993	7420000
1994	10450000
1995	11030000
1996	12560000
1997	11720000
1998	8740000
1999	10200000
2000	7210000
2001	13630000
2002	15620000
2003	8490000
2004	9820000
2005	10450000
2006	16950000
2007	12240000
2008	16370000
2009	16940000
2010	12360000
2011	30470000
2012	20080000
2013	23840000
2014	30450000
2015	51340000
2016	24440000
2017	25680000