More than a year after the oil-price slump began, traders are desperate to determine whether U.S. crude-oil production has started to decline in response to low prices. Mixed and delayed data from the federal government have added to the uncertainty. Market watchers are hoping the next monthly government report, which will offer the first data for May, will help clear up some of the confusion. Here are five things to watch when the U.S. Energy Information Administration, the data-gathering arm of the Energy Department, releases its Petroleum Supply Monthly, expected at 2 p.m. EDT on Friday.