I believe 8% annual inflation has been the normal rate for many years -- slightly decreased following ACA enactment, but rates then increased by a few points due to less-healthy enrollees, so it's a bit of a wash (not counting all the people who now have health insurance, to be sure). Premiums also only cover part of the cost increase; higher deductibles and reduced coverage are also used to defray costs, and aren't as obvious to the end consumers. Finally, plans that don't conform to ACA minimum coverage requirements have been killed off, so some individuals are seeing their rates increase commensurate with their improvement in coverage.