This statistic shows the 12-month percentage of change in the consumer price index, respectively the monthly inflation rate for goods and services in the United States. The data represents U.S. city averages. In economics, the inflation rate is a measure of inflation, the rate of increase of a price index (in the below case: consumer price index). It is the percentage rate of change in price level over time. The rate of decrease in the purchasing power of money is approximately equal. In May 2013, prices went up by 1.4 percent compared to 12 months earlier.