MEXICO CITY, Dec. 17 (Xinhua) -- Mexico's underground economy accounted for 22.7 percent of gross domestic product (GDP) in 2017, the National Statistics and Geography Institute (Inegi) said on Monday.

The figure, which stood at 22.6 percent in 2016 and 22.8 percent in 2015, remained almost unchanged, according to the latest labor report from Inegi.

Last year, 57.1 percent of the country's work force was employed in the underground economy, where workers pay no taxes but also have no protections or rights.

The remaining 42.9 percent of the work force employed in the formal sector accounted for 77.3 percent of GDP.

The informal sector's contribution to GDP set a record high of 24.4 percent in 2009.

Latin America's second-largest economy after Brazil, Mexico saw a 2.1-percent expansion in GDP in 2017.

This year's growth forecast puts it at 2.3 percent.