The Fed’s favorite price index rose 4 percent.

The Federal Reserve’s favorite inflation index climbed by 4 percent in June compared with a year earlier, as a rebounding economy and soaring demand for goods helped to push prices higher.

The gains in the Personal Consumption Expenditures inflation index were the fastest since 2008, but in line with economists expectations. That rapid pace is not expected to last, but how much and how quickly it will fade is the economic question of the moment.

Inflation has been surprisingly rapid this year. Economists knew prices would post strong increases as they were measured against weak figures from 2020, when costs for many common purchases slumped. But the jump has been more intense than most were expecting.

That’s partly because supply bottlenecks have emerged across America’s reopening economy. Computer ship shortages pushed up the prices of electronics and delayed automobile production, causing used car prices to surge. Employers are struggling to hire back workers fast enough to meet returning demand, and prices for restaurant meals and some other services have begun to move higher.

June’s personal consumption expenditure price data may be a high point in the inflationary saga. Last year’s low figures are fading from the data, and many economists expect the rapid pace of price gains to begin to moderate in the coming months.

On a monthly basis, inflation climbed 0.5 percent from May to June, slightly less than the 0.6 percent economists in a Bloomberg survey had expected. The core inflation index, which strips out volatile food and fuel, climbed 3.5 percent over the past year.

How quickly inflation will fall back to the Fed’s 2 percent target, which it tries to hit on average over time, is increasingly uncertain. It is hard to know how quickly the supply chain snarls that have complicated the price picture so far this year will clear up, or whether new ones will emerge. Climbing coronavirus cases around the world could make for continued disturbances in global production and shipping routes, ones that will hit just in time for back-to-school and the holiday shopping season.