A group of large employers in Wisconsin have seen their healthcare costs decrease by 9% over the past two years under a plan put together for the Business Health Care Group. Combined, the 18 unidentified employers provide health benefits for 55,000 employees, retirees and family members. The employer coalition was created to help bring healthcare costs in southeastern Wisconsin in line with other cities in the Midwest. The Group contracted with Humana Inc. in 2005 to put together a health plan solely for its members. That plan, introduced in 2006 and known as Humana Preferred, now covers more than 93,000 people.