The Consumer Price Index (CPI) is calculated by the U. S. Department of Labor. It is a measure of the relative price of a typical market basket of goods in the given year. The percentage increase in the CPI from one year to the next gives one measure of the annual rate of inflation. The following table shows the CPI in December of the given year. Here, C represents the Consumer Price Index, and t is the time in years since December 2008.