The productivity of workers in the United States grew at the slowest pace in nearly two years the U.S. Labor Department said today.

Nonfarm business productivity grew at a seasonally adjusted annual rate of 1.8% from July through September, down from the initial estimate of 1.9% and the lowest rate since the fourth quarter of 2002.

The new figure, based on more complete data, also marked a slowing from the 3.9% productivity pace logged in the second quarter.

In year-on-year terms, the growth rate was 3.1%.

The third-quarter productivity slowdown reflected a surge in workers hours that was not accompanied by an acceleration in the growth of output. For non-farm workers, output grew 4.2% in the third quarter, the same rate as in the second quarter. But workers’ hours rose 2.4%, the biggest increase in five years.

Meanwhile, unit-labor costs rose 1.8%, up from the government’s initial estimate of a 1.6% increase. Hourly compensation, adjusted for inflation, rose 1.8%, compared with a 1.1% increase in the second quarter.

Manufacturers of non-durable goods enjoyed the biggest productivity gains during the third quarter. Labor productivity among such companies increased 5.4%, slowing from an 8.7% rate in the second quarter. The overall manufacturing industry saw a productivity increase of 4.6%, slightly more than half the rate recorded in the second quarter.