HOUSTON (AP) — The number of rigs exploring for oil and natural gas in the U.S. increased by 16 this week to 653.

A year ago, 700 rigs were active. Depressed energy prices have curtailed exploration, although the rig count has been rising in recent weeks.

Houston oilfield services company Baker Hughes Inc. said Friday that 523 rigs sought oil and 129 explored for natural gas this week. One was listed as miscellaneous.

Oklahoma gained six rigs, Texas gained four, Alaska increased by three and Colorado, Louisiana, New Mexico, North Dakota, Ohio, Pennsylvania and Wyoming each added one.

West Virginia declined by two and Arkansas lost one.

California, Kansas and Utah were unchanged.

The U.S. rig count peaked at 4,530 in 1981. It bottomed out in May at 404