FACTBOX-Mexico's oil industry

Aug 5 (Reuters) - Here are some facts about Mexico's state-controlled oil industry as lawmakers debate proposals to give private companies a bigger role and help bolster falling output.

* Mexico is the world's No. 6 producer of crude oil by volume and the No. 10 exporter. It is a top supplier to the United States.

* The industry is in a critical situation with yields at Cantarell -- a sprawling offshore oil field discovered in 1971 when a fisherman noticed oily bubbles in the Gulf of Mexico -- slipping fast. New fields being developed are not enough to make up for the shortfall.

* Mexico nationalized its oil industry in 1938 and created state-run monopoly Pemex. Mexico has some of the tightest restrictions on private investment in energy in the world, with stricter rules than Cuba, China and Russia.

* Despite its large oil reserves, a refining shortfall means Mexico imports about 40 percent of its gasoline. It also imports some natural gas.

* Mexico's oil reserves are declining due to years of low investment under seven decades of one-party rule until 2000.

* Taxes on oil exports fund about one-third of government spending, but this tax burden has held back Pemex's spending on exploration and new refineries. Two recent tax cuts slightly eased Pemex's burden.

* Mexico produces about 2.9 million barrels of crude per day, down from a peak of 3.4 million bpd in 2004, and exports about 1.5 million bpd. (Reporting by Jason Lange; Editing by Kieran Murray)