Falling oil prices pushed US consumer prices into their sharpest monthly drop in six years in December, according to government data released Friday.
The Labor Department said its consumer price index fell 0.4 percent last month, in line with analyst expectations. The CPI declined 0.3 percent in November.
Energy accounted for all of the decline, the steepest monthly fall since December 2008 amid the financial crisis that triggered the Great Recession.
Energy prices slumped 4.7 percent from November, reflecting the rapid dive in global crude prices since June that has more than halved their value.
Year-over-year, energy prices dived 10.6 percent, the steepest slide since 2008.
Gasoline prices plunged 9.4 percent in December, and have shed 22.4 percent in the second half of the year.
Food prices rose 0.3 percent in December, their largest increase since September.
Excluding food and energy prices, the so-called "core" CPI was unchanged.
Inflation has remained well below the Federal Reserve's 2.0 percent inflation target as the economy slowly recovers from the deep 2008-2009 recession.
The CPI rose 0.8 percent in 2014, the second-weakest annual inflation in 50 years in the United States, after a 0.1 percent rise in 2008. "This is notably lower than the 1.3 percent change for the 12 months ending November," the department said in its report.
The less-volatile core inflation was up 1.6 percent.