HOUSTON (AP) - Oilfield services company Baker Hughes Inc. says the number of rigs exploring for oil and natural gas in the U.S. increased by nine this week to 1,866. The Houston firm said in its weekly report Friday that 1,536 rigs were exploring for oil and 326 for gas. Four were listed as miscellaneous. A year ago there were 1,771 active rigs. Of the major oil- and gas-producing states, Oklahoma gained eight rigs, Texas gained five Wyoming gained two and Alaska and California each increased by one apiece. North Dakota lost five rigs while Kansas, New Mexico and Ohio each decreased by one. Arkansas, Colorado, Louisiana, Pennsylvania, Utah and West Virginia were all unchanged. The U.S. rig count peaked at 4,530 in 1981 and bottomed at 488 in 1999.