A report by ADP Research Institute today showed that U.S. private employers added 250,000 jobs in December, marking the biggest monthly increase since March, Reuters reported. Economists surveyed by Reuters had forecast the ADP National Employment Report would show a gain of 190,000 jobs, with estimates ranging from 165,000 to 225,000.Private payroll gains in the month earlier were revised down to 185,000 from an originally reported 190,000 increase. The report is jointly developed with Moody’s Analytics.