Six of Wisconsin?s largest health care systems are forming a statewide network to contract with insurers, and to share what works best for each group. The partnership includes health systems that serve about 90-percent of Wisconsinites ? Aurora Health of Milwaukee, U-W Health of Madison, Gundersen of La Crosse, Aspirus of Wausau, Bellin of Green Bay, and ThedaCare of Neenah.