A line chart of Percent of Total Revenues versus Budget Years.

U.S. Congressional Budget Office’s Past Inaccuracies in Projecting the Primary Surplus, Compared with the Constructed 90 Percent Confidence Range. Note: Each thin line represents the actual inaccuracies of the set of projections made in a given year. The thick lines represent the 90 percent confidence range constructed from CBO’s statistical model for inaccuracies. That range encompasses nearly all of CBO’s past record. (Image courtesy of the Congressional Budget Office.)