Oilfield services company Baker Hughes Inc. says the number of rigs exploring for oil and natural gas in the U.S. declined by nine this week to 700. The Houston firm said Wednesday 538 rigs sought oil and 162 explored for natural gas amid depressed energy prices. A year ago, 1,840 rigs were active. Among major oil- and gas-producing states, North Dakota and Wyoming each declined by three, Arkansas and Louisiana were down two, and Alaska, Colorado and Texas dropped one apiece. Oklahoma gained two rigs. Kansas and New Mexico were up one each. California, Ohio, Pennsylvania, Utah and West Virginia were unchanged. The U.S. rig count peaked at 4,530 in 1981 and bottomed at 488 in 1999. The count, normally released on Fridays, was early this week because of Christmas.