I believe it is based on the utilization of credit (so the total sum, compared period to period)
It's gone up. Considerably. Contrary to what that picture shows a lot of households are absorbing the combination of shrinking portions of food / rising prices with cards.
Is that just straight usage or outstanding balance?
My usage of credit cards has changed over the years.
It used to be I used them very sparing for infrequent large purchases. Then paid them off in installments.
Now I use a credit card for most regular purchases because of the cash back and security if the card number gets compromised. I also pay it off in full every month.
So my usage has increased by 10x but my outstanding balance is 0.