Crude oil production fell to 1.9 million barrels a day last year from a peak of 3.5 million in 1972.

Domestic oil production, meanwhile, fell to 7.2 million barrels a day - the lowest level since 1961.

All told, gasoline inventories fell to 190.1 million barrels as of Friday, down 8.6 percent from the period a year earlier.

In the North Sea, for example, production is expected to fall almost by half, to three million barrels a day, in 2020.

Gasoline demand fell by 6.4 percent, to 7.88 million barrels a day, in the week ended May 17, according to the institute.

Crude oil imports fell 4.4 percent, to 421,086 barrels.

The company's daily production of crude oil has fallen to 850,000 barrels a day from about 950,000 three years ago.

For 1991, sales abroad fell to 1.1 million barrels a day, from 2 million the year before.

Last year its worldwide crude oil reserves fell 20 percent, to 718 million barrels, according to the company's annual report.

Refinery operations also fell, to 1.3 million barrels a day from 1.9 million.