HOUSTON (AP) — The number of rigs exploring for oil and natural gas in the U.S. declined by 15 this week to 913. That's up from the 553 rigs that were active a year ago. Houston oilfield services company Baker Hughes said Friday that 736 rigs sought oil and 177 explored for natural gas this week. Among major oil- and gas-producing states, Texas lost eight rigs, Alaska and Wyoming each declined by two and New Mexico and Utah each lost one. Arkansas, California, Colorado, Kansas, Louisiana, North Dakota, Ohio, Oklahoma, Pennsylvania and West Virginia were unchanged. The U.S.