Year	current US$
1995	155000000
1996	154000000
1997	151000000
1998	155000000
1999	155000000
2000	158000000
2001	160000000
2002	160000000
2003	188000000
2004	227000000
2005	140000000
2006	135000000
2007	158000000
2008	160000000
2009	181000000
2010	180000000
2011	178000000
2012	439000000
2013	426000000
2014	428000000
2015	278000000
2016	244000000
2017	264000000
2018	112000000
2019	45000000
2020	8000000