A merger of Wisconsin-based Aurora Health Care and Illinois-based Advocate Health Care would create one of the largest non-profit health care systems in the country. Merger plans were announced Monday. When it’s final, the newly-named Advocate Aurora Health would serve almost three-million patients each year, would operate more than two dozen hospital and have more than 73-thousand employees. Advocate and Aurora would maintain their current headquarter locations. Federal and state regulatory agencies still have to give their approval. With no interruptions, the deal should close by the middle of next year.