Food prices continued to rise in May, for the ninth month in a row, according to the latest figures from the U.S. Bureau of Labor Statistics.

The BLS food index increased 0.7% in May, following a 1.5% increase in April. The May increase was mostly driven by increases in the price of protein of various types, with beef going up 10.8%, its largest-ever monthly increase.

The indexes for dairy, fruit and vegetables were up slightly. Cereals and bakery products were both down 0.2% after having risen 2.9% in April.

Over the last 12 months, the food-at-home index has gone up 4.8%, with all six major grocery store food group indexes rising over that span. Again, protein led the way, especially beef, which rose 18.2%.