Source: Federal Reserve Bank of Philadelphia  

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

Units:  Percent, Not Seasonally Adjusted

Frequency:  Quarterly, End of Quarter

The share of active credit card accounts that have a positive balance subject to a promotional APR. Promotional APRs are defined as APRs priced at a rate below the account holder's normal purchase APR at the end of the most recent cycle. 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.