Year	constant 2015 US$
1991	380000
1992	8530000
1993	45870000
1994	71590000
1995	51120000
1996	97240000
1997	86030000
1998	67160000
1999	83160000
2000	76560000
2001	98180000
2002	81530000
2003	71620000
2004	62200000
2005	66250000
2006	64370000
2007	59150000
2008	57750000
2009	63350000
2010	30530000
2011	86180000
2012	83450000
2013	94190000
2014	56330000
2015	58290000
2016	12560000
2017	70980000