Oil futures maintained strong gains Friday after data showed the number of active U.S. drilling rigs fell this week. The number of oil rigs declined by four to 858, according to oilfield-services firm Baker Hughes. The number is up 102 from a year ago. The number of gas rigs fell by 1 to 187 and stands 3 higher than at this time in 2017. West Texas Intermediate crude for August delivery on the New York Mercantile Exchange was up 72 cents, or 1%, at $74.17 a barrel, on track for a weekly rise of more than 8%.