Consumer prices resumed their upward trek in January after a six-month hiatus, the Labor Department reported Friday.

The Consumer Price Index rose 0.3% in January on a seasonally adjusted basis, 0.4% before adjustment. However, on a year-over-year basis, prices remained flat with last January at an index of 211.143, signaling that, at least for this month, annual inflation was nonexistent. That has not happened in some 50 years.

Among the components of the CPI, the energy index rose 1.7%, its first increase in six months, but it remained 31.4% below its July 2008 peak. The gasoline index rose 6.0% in January after a 19.3% decline in December. The fuel oil index fell 3.7%; natural gas declined 3.6%.

The food index increased 0.1% after a flat December. The food index is up 5.3% year-over-year.

The housing index was flat for the second straight month, but the shelter (rental) index rose 0.2%. During the past year, the housing index has risen 2.2% and the index for shelter 1.8%. Within shelter, the indices for rent and owners¹ equivalent rent both rose 0.3% in January after rising 0.2% and 0.1%, respectively, in December.