Gov. Mark Dayton claimed a victory for taxpayers on Tuesday, saying efforts to curb the state's health spending have delivered an estimated $73 million bonus from four health insurance plans. Last year, in the face of rising health care costs and a state budget shortfall, Minnesota's four largest nonprofit insurers agreed to a one-time limit on profits from insurance coverage to low-income Minnesotans. Blue Cross and Blue Shield of Minnesota, HealthPartners, Medica and UCare capped their operating margin at 1 percent and agreed to return the rest to taxpayers.