Year	constant 2015 US$
1997	85220000
1998	53190000
1999	142630000
2000	170300000
2001	166260000
2002	193090000
2003	146000000
2004	135390000
2005	183730000
2006	235230000
2007	255090000
2008	267790000
2009	226740000
2010	438800000
2011	400830000
2012	431700000
2013	316860000
2014	469800000
2015	317280000
2016	262050000
2017	235810000