Year	US Dollars, Monthly Level
1971-01-01	3243012018.327990
1972-01-01	4238383694.937130
1973-01-01	6156403613.153600
1974-01-01	12574823658.617102
1975-01-01	12221526376.092500
1976-01-01	12359151489.296000
1977-01-01	12047725822.542000
1978-01-01	13715230850.996100
1979-01-01	17956175540.706400
1980-01-01	22947988256.646202
1981-01-01	22145822280.575700
1982-01-01	19420236433.914200
1983-01-01	15476064699.360700
1984-01-01	13935530392.396600
1985-01-01	13120372098.453600
1986-01-01	13949443442.271000
1987-01-01	15045683116.137100
1988-01-01	14579371066.880300
1989-01-01	18152240613.648700
1990-01-01	20496927493.935400
1991-01-01	20921880986.522003
1992-01-01	20465008444.140100
1993-01-01	25087129712.115200
1994-01-01	32824059454.259697
1995-01-01	50154538095.577400
1996-01-01	53012148084.769005
1997-01-01	59296364345.313700
1998-01-01	57542282097.233505
1999-01-01	49078895094.417595
2000-01-01	56023517584.670204
2001-01-01	55476871906.765300
2002-01-01	47027269443.413300
2003-01-01	48252994435.237495
2004-01-01	62360543733.402100
2005-01-01	73470648316.878200
2006-01-01	91073351532.846900
2007-01-01	119797566962.726000
2008-01-01	171895758613.324000
2009-01-01	127370525276.694000
2010-01-01	180755014264.455020
2011-01-01	226091077102.615000
2012-01-01	223806495504.694000
2013-01-01	238928735643.311980
2014-01-01	228851632547.849980
2015-01-01	171621760522.878000
2016-01-01	137787158606.110020
2017-01-01	151179428234.849000