WASHINGTON (AP) ― The U.S. economy grew even faster in the third quarter than initially thought, posting the strongest six months of growth in more than a decade and pulling further ahead of other big economies of the world.

The gross domestic product, the country’s total output of goods and services, expanded at a healthy 3.9 percent annual rate in the July-September period, the Commerce Department reported Tuesday. That’s a notable jump from its first estimate of 3.5 percent. The revision was propelled higher by more robust consumer and business spending.

Together with a 4.6 percent surge in the spring, the country has recorded its biggest back-to-back quarterly performance since 2003.

“The question of whether the economy is accelerating or will accelerate is no longer a question; we can say somewhat definitively that the economy has already accelerated,” said Dan Greenhaus, chief strategist at BTIG, in a research note.

In contrast, other advanced economies are struggling.