Baker Hughes          BKR,         +0.27%        on Friday reported that the number of active U.S. rigs drilling for oil was up by four to 584 this week. That followed an increase of six oil rigs the week before, Baker Hughes data show. The total active U.S. rig count, which includes those drilling for natural gas, climbed by seven to 740, according to Baker Hughes. Oil prices continued to trade sharply lower. June West Texas Intermediate crude          CLN22,         -6.05%        was down $7.77, or 6.6%, at $109.82 a barrel on the New York Mercantile Exchange.