Individual health insurance premiums in the years before President Barack Obama signed the Affordable Care Act into law had large average increases and a high variability in rate hikes across different states and insurers, a study released Thursday found. Nonpartisan foundation The Commonwealth Fund said its findings provide the most comprehensive data assembled to date for use as a benchmark comparison with Affordable Care Act-era price increases, which have begun being released for the 2015 plan year. The study, which examined the years 2008 to 2010, found that health insurance premiums for people buying coverage on their own—not as part of an employer-provided plan—grew more than 10 percent on average.