A total of 15.5 million Americans had major medical coverage

... in the individual insurance market as of December 31, 2014, a 46% increase during the first year that plans could be purchased through the Affordable Care Act’s marketplaces, according to a recent analysis.

Source: "Data Note: How Has the Individual Insurance Market Grown Under the Affordable Care Act?," The Henry J. Kaiser Family Foundation, April 29, 2015, http://kff.org/private-insurance/issue-brief/data-note-how-has-the-individual-insurance-market-grown-under-the-affordable-care-act/