Source: Federal Reserve Bank of Philadelphia  

Release: FR Y-14M Large Bank Credit Card and Mortgage Data  

Units:  U.S. Dollars, Not Seasonally Adjusted

Frequency:  Quarterly, End of Quarter

The average quarterly total purchase volume per active credit card account with a current credit score less than 660. An account's purchase volume is the net sum for the three months within the quarter. Active credit card accounts are defined as credit card accounts that are open and have had debit, credit, or balance activity in the last 12 months.

For more detail see the methodology.