Opec deepened compliance with an oil supply-cutting deal in December due to a further decline in Venezuelan output and extra cuts by Gulf exporters, a Reuters survey found, showing strong commitment to the deal despite higher prices.

Adherence to the curbs rose to 128 percent from 125 percent in November, the survey found. The United Arab Emirates for the first time since the deal took effect in January 2017 pumped below its Opec target, joining Saudi Arabia and Kuwait.

The Organisation of the Petroleum Exporting Countries is reducing output by about 1.2 million barrels per day (bpd) as part of a deal with Russia and other non-Opec producers. The pact will run until the end of 2018.

Oil hit its highest since May 2015 this week, supported by falling inventories, strong demand and high Opec compliance. Many producers, still suffering from a 2014 price collapse, are enjoying the rally and the extra revenues.

“We are all pleased about it,” one official in an Opec country said of the early 2018 price rise.