According to a recent study of almost 400 physician networks in silver-level plans sold nationally in 2014:

• 11% of the plans covered fewer than 10% of physicians in the plan’s region
• 30% of the plans covered between 10% and 25% of physicians in their region
• Only 11% of the plans covered at least 60% of physicians in their region

 Source: "The Skinny on Narrow Networks in Health Insurance Marketplace Plans," The Robert Wood Johnson Foundation, June 2015, http://www.rwjf.org/content/dam/farm/reports/issue_briefs/2015/rwjf421027