BERLIN (AP) — The German economy accelerated last year to grow by 2.2 percent, putting in its strongest performance for six years thanks primarily to increasing demand at home, official data showed Thursday.

The figure released by the Federal Statistical Office was the strongest since 2011, when Europe's biggest economy grew by 3.7 percent. Gross domestic product expanded by 1.9 percent in 2016 and 1.7 percent in 2015.

Household spending by Germans was up 2 percent last year, while investment in machinery and other equipment was up 3.5 percent.

Exports, a traditional strength of the German economy, grew by 4.7 percent, a much stronger performance than the previous year's 2.6 percent. But they were outpaced by imports, which expanded by 5.2 percent, up from 3.9 percent in 2016. Overall, foreign trade contributed 0.2 percentage points to last year's economic growth.

The statistics office didn't immediately release a figure for fourth-quarter growth in its preliminary 2017 growth report.

An official reading is expected next month, after economic data for December become available.