Further below is an extract of Segment E.  'Revenues for Credit Card Companies Arise from Interest, Not Transaction Interchange Fees' of the below listed
Paper 'An Assessment from Behavioural Law and Economic Contentions and What We Know Empirically about Credit Card Use by Consumers'
from the afore-mentioned publication dated Jun 21, 2015 titled 'Supreme Court Economic Review, Volume 22'.

Professor Oren Bar-Gill graduated from (Law and Economics) Harvard Law School is a law professor at New York University School of Law. Subjects taught by Oren Bar-Gill include Law & Economics. 
In the further below extract, Professor Bar-Gill contends that:

1. Thus, while interchange fees are still a minority of the revenues from credit cards, they are growing in size.

2. Information on the growth of interchange fee revenue relative to financing charges is available from industry sources.

3. SourceMedia collected revenue and cost information and made the composite figures available annually in the May 2011 issue of PaymentsSource
   magazine and its other publications. A time series of these data 1991 to 2011 shows that interest (excluding late payment fees) is indeed the primary source for credit card issuers, but it is not the only source and it has been declining relative to interchange revenue for years.

4. Specifically, revenue from interchange, which arises from fees charged by card issuers to merchants who accept the cards for payments by consumers has been rising steadily until it represented 23% of revenues of card issuers, the most recent data, up from 10% in 1991.