Oilfield services company Baker Hughes Inc. says the number of rigs exploring for oil and natural gas in the U.S. increased by six this week to 1,931.

The Houston firm said Friday in its weekly report that 1,592 rigs were exploring for oil and 338 for gas. One was listed as miscellaneous. A year ago there were 1,768 active rigs.

Of the major oil- and gas-producing states, Alaska gained three rigs; Kansas, New Mexico and North Dakota each increased by two; and Colorado, Ohio and Pennsylvania were up one apiece.

Texas and Louisiana each declined by two and California was down one.

Arkansas, Oklahoma, Utah, West Virginia and Wyoming were unchanged.