MGE Energy provides electric service to 161,000 customers and natural gas service to 173,000 customers in Madison, Wisconsin, and surrounding areas. Nearly 90% of customers are residential. The company also owns a 3.6% stake in American Transmission Co. MGE owns interests in two coal power plants that earn guaranteed fixed rates of return, contributing about 20% of earnings. MGE's generation mix is 40% coal, 21% renewable energy, 17% natural gas, and third-party purchased power.