This chart shows the monthly, seasonally adjusted Consumer Price Index for the U.S. It is shown with a log scale so that the slope of the line illustrates the amount of consumer price inflation at any point in time. The data is from St. Louis Federal Reserve Series CPIAUCSL. This data is scaled so that the index value is 100 at the current data point.
mccormick-charts.com: St. Louis Federal Reserve Series CPIAUCSL
Wikipedia: United States Consumer Price Index