Figures showed that U.S. consumer prices had climbed 12.4 percent during 1980, marking the second straight year of double-digit inflation. The report confirmed the nation’s longest spell of high inflation since the end of World War I. The 1979 inflation rate had been 13.3 percent. Not since 1918-19, when the United States was returning to a peacetime economy, had inflation exceeded 10 percent for two years running. Many of the figures had been compiled with the aid of Kansas University economics experts.