You may begin with:

• Statista provides quick statistics on the topic. Just search by keyword. 
• Nilson Report Publishes statistics and in-depth articles on the credit card system and other payment methods. An index to issues is available online. In print in the current periodicals section of the Stamps Reading Room. Contact Baker Library for digital issues 2022 to the present.
• The Federal Reserve collects statistics on Consumer Credit.

Additional resources: 

• IBIS World provides market reports on the topic. You may begin a search by using: "credit card" payment
• Bloomberg Academic type CCR and hit GO to display credit card reports from issuers.