Year	constant 2015 US$
1975	40000
1977	30000
1979	50000
1980	80000
1981	60000
1982	50000
1983	70000
1984	70000
1985	140000
1986	110000
1987	130000
1988	330000
1989	80000
1990	270000
1991	620000
1992	620000
1993	650000
1994	15210000
1995	3820000
1996	4660000
1997	4040000
1998	3890000
1999	8030000
2000	5460000
2001	15540000
2002	23200000
2003	26050000
2004	18880000
2005	11350000
2006	21460000
2007	27140000
2008	31200000
2009	24630000
2010	24270000
2011	27950000
2012	26630000
2013	22760000
2014	19180000
2015	31620000
2016	22680000
2017	24160000