Tokyo’s inflation outpaced forecasts to hit 4% for the first time since 1982, suggesting the underlying price trend is stronger than thought by economists, a factor that could further fuel speculation the Bank of Japan will adjust policy again.

Consumer prices excluding fresh food climbed 4% in the capital in December as processed food and energy costs continued to mount and a majority of tracked items got more expensive, according to the ministry of internal affairs on Tuesday. Economists had forecast a 3.8% rise.

Tokyo inflation is a leading indicator of the nationwide trend, and the faster pace suggests the country’s price growth also likely accelerated in December. The figures are the last key price data before the central bank meets again next week to decide on policy and update its inflation forecasts.