Although employer-sponsored health insurance forms the backbone of the health insurance system in the United States, small businesses are finding it increasingly difficult to provide their workers with comprehensive coverage. In 2007, only 25 percent of employees in small businesses had coverage through their own employers, compared with 74 percent of workers in large firms. Because there are few sources of affordable coverage outside the employer-based system, millions of employees in small businesses are uninsured or have inadequate health insurance. In 2007, 52 percent of workers in small businesses were uninsured or underinsured during the year, compared to half as many employees in large businesses. Congressional health reform bills to reform the health system include provisions specifically aimed at helping small businesses and their employees gain access to affordable, comprehensive coverage.