Reference:
2008
September 2008: $616.09 million (Source)
August 2008: $550.67 million (Source)
July 2008: $591.1 million (Source)
June 2008: $872.6 million (Source)
May 2008: $536.9 million (Source)
April 2008: $654.7 million (Source)
March 2008: $945.6 million (Source)
February 2008: $668.7 million (Source)
January 2008: $610.6 million (Source)
2007
December 2007: $2.37 billion (Source)
November 2007: $1.3 billion (Source)
October 2007: $513.9 million (Source)
September 2007: $653.6 million (Source)
August 2007: $488.0 million (Source)
July 2007: $419.2 million (Source)
June 2007: $543 million (Source)
May 2007: $380.8 million (Source)
April 2007: $399 million (Source)
March 2007: $574 million (Source)
February 2007: $441 million (Source)
January 2007: $549 million (Source)
2006
December 2006: $1.7 billion (Source)
November 2006: $804 million (Source)
October 2006: $369 million (Source)
September 2006: $446 million (Source)
August 2006: $397 million (Source)
July 2006: $386 million (Source)
June 2006: $444 million (Source)
May 2006: $286 million (Source)
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