State and industry data show the number of rigs actively exploring for or producing oil and natural gas in the top three U.S. producing states declined. North Dakota state data show 84 active drilling rigs in service as of Monday. That’s down from the 86 reported last week, 108 year-on-year and the lowest on record for the state in more than five years. Oil companies are spending less on exploration and production because crude oil markets have been depressed for nearly a year. That leaves energy companies with less capital to invest in exploration and production. North Dakota produced 1.17 million barrels of oil per day in February, the last full month for which data are available. […]