The U.S. economy increased at an annual rate of 5.7 percent in the fourth quarter of 2009, the quickest pace in more than six years, the Commerce Department reported Friday.

The acceleration in the real GDP in the fourth quarter primarily reflected positive contributions from private inventory investment, exports, and personal consumption expenditures (PCE), said the department while releasing the report.

The 5.7 percent increase in the fourth quarter, the best showing since 2003, was also much more energetic than the 4.6 percent increase that economists had expected.

In the third quarter of 2009, the real GDP expanded at 2.2 percent. The two straight quarters of growth last year followed a record four quarters of economic decline

The GDP measures the value of all goods and services produced within the United States.

In the September-December period, consumer spending, which accounts for two thirds of overall economic activity, rose at an annual rate of 2.0 percent due to the economic stimulus package, compared with an increase of 2.8 percent in the third. It added 1.44 percentage points to the fourth quarter change in the real GDP.

Durable goods decreased 0.9 percent, in contrast to an increase of 20.4 percent. Nondurable goods increased 4.3 percent, compared with an increase of 1.5 percent. Services increased 1.7 percent, compared with an increase of 0.8 percent.

Exports of goods and services surged 18.1 percent in the fourth quarter, compared with an increase of 17.8 percent in the third. Meanwhile, imports of goods and services increased 10.5 percent, compared with an increase of 21.3 percent.

One of the main drive on growth was private inventories sector, which added 3.39 percentage points to the fourth quarter change in the real GDP after adding 0.69 percentage point to the third quarter change.

Motor vehicle output added 0.61 percentage point to the fourth quarter change in the real GDP after adding 1.45 percentage points to the third quarter change.

Final sales of computers subtracted 0.03 percentage point from the fourth-quarter change in the real GDP after subtracting 0.08 percentage point from the third-quarter change.

For the whole of 2009, the economy contracted 2.4 percent, the biggest decline since 1946, said the Commerce Department.