Inflation in the United States slowed in November, a key index based on personal consumption expenditures showed Friday. The PCE index slowed slightly to a pace of 2.5 percent year-on-year, Commerce Department figures showed, with the core inflation figure -- excluding volatile food and energy costs -- stable from the previous month at 1.7 percent. The index is used as a reference for inflation by the US Federal Reserve in setting monetary policy and interest rates. Inflation has remained subdued despite the central bank having kept its main rate at an ultra-low 0-2.5 percent for three years running.