Japan’s inflation has hit 4% for the first time in more than four decades, an outcome likely to keep speculation of a monetary policy change smoldering as prices grow at twice the pace targeted by the Bank of Japan.

Consumer prices excluding fresh food rose 4% in December from a year ago, the internal affairs ministry reported Friday.

The result matched economists’ estimate, and was led by further gains in energy and food costs. Prices of processed food grew at the fastest pace since 1976, while electricity and gas prices both continued to jump more than 20% from the year before.