Mexico City, Mexico - As state-owned Petroleos Mexicanos prepares for an influx of foreign investment, Mexico's oil production last year was its lowest on record.

Mexico produced 2.35 million daily barrels of oil in December, according to data the Mexico City-based company posted online Wednesday. Based on that preliminary rate and averaged with other monthly data this year, Pemex produced 2.43 million barrels a day 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 output since at least 1990, when the government first began releasing data. Daily production has fallen by almost 1 million barrels 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 barrels by 2018. President Enrique Pena Nieto passed legislation last year to allow private producers such as Chevron and Exxon Mobil to pump crude in Mexico for the first time in 76 years.

Pemex originally forecast production of 2.5 million barrels a day for 2014, a number that was revised to 2.35 million daily barrels in August to reflect water content and inaccurate measuring systems.

Pemex forecasts oil production will reach 2.4 million barrels per day 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.