Crude oil production from Norway came in lower in May than for April, but was still up 2 percent year-on-year, government data released Friday show.

The Norwegian Petroleum Directorate, the nation's energy regulator, said preliminary data indicate oil production averaged 1.55 million barrels per day. That's a decline of more than 5 percent from April, but 2 percent higher than May 2015.

"The oil production is about 1.5 percent above the NPD's prognosis for the month," the agency said in a statement.

April production levels were 3 percent higher than expected. The government estimates there are roughly 18 billion barrels of oil equivalent yet to be discovered in Norwegian waters and new fields, like the giant Johan Sverdrup, could add to overall production once commercial operations begin.

Despite the recent recovery in crude oil prices, the Norwegian government said it expects the economic pressures from the market downturn to linger. Mainland gross domestic product increased during the first quarter by 1.3 percent, though the economy has been under pressure for seven straight fiscal quarters.

Statistics Norway said demand pressures on the petroleum industry started to wane at the end of 2013. That, in turn, put negative pressure on the Norwegian economy, which as a main oil and gas exporter to the European market relies heavily on the industry for revenue.

The overall downturn, the government said, is moving closer to its third year the economy is now moving toward a restructuring phase. Nevertheless, the government said the petroleum era is far from over for the Norwegian economy.