How rewards programs for the rich could push credit-card costs higher — even though interest rates are falling

While interest rates plateaued and then moved steadily lower this year, credit card costs have headed in the opposite direction.  
Banks have increased credit card interest rates to mark up for profit losses from increasingly generous rewards programs, according to the Wall Street Journal.
Perks like free travel have helped push the average annual percentage rate on credit cards up to nearly 17% in August, its highest level in at least 25 years. 
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