New York's medical community worries that adding 1.1 million people to insurance rolls under the federal health care overhaul will overwhelm primary care physicians, many of whom are already swamped. Federal data showed nearly 18,000 physicians providing primary care at the start of 2011 in a state with 19.6 million residents. That was the 11th-best ratio among states. The New York Department of Health estimates that 2.7 million people are uninsured, and that 615,000 individuals and 450,000 small-business employees will enroll through the New York Health Exchange for coverage starting in 2014.