The numbers: The productivity of American workers soared in the first quarter and pushed the increase over the past year to the highest level since 2010, a potentially great sign for the U.S. economy.

The productivity of American workers increased at a 3.6% annual pace from January through March, the government said Thursday. That’s the biggest gain since the fall of 2014.

Economists polled by MarketWatch had forecast a 2.9% increase.

Until very recently, the growth in productivity has been stubbornly weak and a major black mark on a nearly 10-year-old expansion. It’s averaged just 1.3% a year since 2007, well below the 2.7% rate from 200 to 2007 or a postwar average of slightly more than 2%.

Productivity has increased 2.4% in the past 12 months, the fastest clip since 2010, a period when it increased largely because companies cut hoards of jobs during the Great Recession and basically forced remaining workers to do more with less.

Higher productivity is a magic elixir or sorts that over time allows an economy to grow faster without stoking inflation.

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What happened: Companies increased the amount of goods and services they produced, known as output, by a healthy 4.1%. And they managed it even though the hours workers spent on the job rose a mild 0.5%.

What’s more, unit-labor costs declined 0.9%. Over the past year unit-labor costs — how much it costs to make each product — have risen a scant 0.1% to mark the smallest increase since 2013.

The decline in unit-labor costs adds to a slew of recent evidence that inflation has waned after a sharp burst last year and poses little threat to the economy.

The increase in productivity in the fourth quarter, meanwhile, was revised down to 1.3% from 1.9%.

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Big picture: The low level of productivity in the past decade has puzzled economists for years, but fresh evidence suggests some of the recent gains might be longer lasting. Companies have invested more in technology and workers in the past few years, the first step in enabling them to produce more goods and services in the same amount of time.

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The potential benefits of higher productivity are immense: Higher profits, rising wages and an improved standard of living for American families.

What’s still unclear, however, is whether the recent increase can be sustained. Business investment tapered off toward the end of 2018 and the outlook for this year is uncertain.

Some economists also contend that a bout of fiscal stimulus — tax cuts and more government spending — has given productivity a temporary boost.

What they are saying?: Chief economist Ian Shepherdson of Pantheon Macroeconomics said the rebound in productivity is impressive, but it “probably can’t be sustained at this pace.”