Year	US Dollars, Monthly Level
1991-01-01	63666761938.603004
1992-01-01	54309162123.492300
1993-01-01	56637650531.499600
1994-01-01	67560652584.102600
1995-01-01	81456703733.589800
1996-01-01	88420478136.241000
1997-01-01	85924993075.473100
1998-01-01	74019786082.508010
1999-01-01	69117319347.115200
2000-01-01	99586282336.732300
2001-01-01	97029876983.835800
2002-01-01	101714695850.778990
2003-01-01	128923413936.440000
2004-01-01	176885626111.707000
2005-01-01	239316450422.909030
2006-01-01	297411544428.982000
2007-01-01	344659342006.983030
2008-01-01	464903735908.201000
2009-01-01	295497305602.045000
2010-01-01	393059908554.930000
2011-01-01	515281956557.543000
2012-01-01	528982883339.647000
2013-01-01	522233250572.322000
2014-01-01	497716082296.900000
2015-01-01	342770799748.230000
2016-01-01	281271895890.028000
2017-01-01	353764711434.783000