Mexico is headed for its lowest annual oil production on record as state-owned Pemex prepares for an influx of foreign investment.

Mexico produced 2.35 MMbbl/d of oil this month through Dec. 28, according to data the Mexico City-based company posted online. Based on that preliminary rate and averaged with other monthly data this year, Pemex produced 2.43 MMbbl/d in 2014, for a 10th consecutive annual output decline.

That figure, which may be further reduced to reflect measurement problems announced in August, would be the lowest annual output since at least 1990, when the government first began releasing data. Daily production has fallen by almost 1 MMbbl since a 2004 peak.

Mexico’s Energy Ministry sees outside investment ending declines in the world’s ninth-largest oil producer, with output expected to increase 500,000 bbl by 2018. President Enrique Pena Nieto passed legislation last year to allow private producers such as Chevron Corp. and Exxon Mobil Corp. to pump crude in Mexico for the first time in 76 years.

Pemex originally forecast production of 2.5 MMbbl/d this year, a number that was revised to 2.35 MMbbl/d in August to reflect water content and inaccurate measuring systems.

Pemex forecasts oil production will reach 2.4 MMbbl/d in 2015, according to exploration and production director Gustavo Hernandez. The company may revise historic production figures from the first six months of the year to reflect inaccurate measurements, he said.