Credit card use has a life cycle with three distinct phases, according to a Federal Reserve Bank of Boston study of Equifax data, which plotted out how credit card debt and credit limits change over time for Americans ages 20 to 80.

Youths start out with not much credit, but they quickly gobble up most of it. From there, credit card debt starts rising, but credit card limits rise even faster.

A cardholder’s late 40s see the start of phase two, where median debt begins tapering downward. Because credit limits continue rising to a peak in people’s mid-60s, credit utilization — or the percentage of available credit being used — drops from 16 percent at age 47 down to 8 percent by age 64.

The third and last phase typically begins in an Americans’ late 60s, when credit limits stop climbing and begin to descend. With debt declining as well, credit utilization falls below 5 percent around age 74.

The study, “Consumer Revolving Credit and Debt Over the Life Cycle and Business Cycle,” by Scott L. Fulford and Scott Schuh, drew from a 5 percent sample of every credit account in the United States from 1999 to 2014 from the credit reporting agency Equifax. Demographics of the sample were determined to match the overall population very closely since the vast majority of Americans over the age of 18 has a credit bureau account.