Health spending in the U.S. climbed to $2.7 trillion and constituted 17.9 percent of the nation’s gross domestic product (GDP) in 2011. A recent report released by actuaries at the Centers for Medicare and Medicaid Services (CMS) found that health spending as a share of GDP remained steady at 17.9 percent from 2009 through 2011. Despite that stability, some analysts warn that, as the economy improves and the population ages, cost increases could again accelerate. Effects of cost constraining provisions in the Patient Protection and Affordable Care Act (PPACA) are largely unknown, since major provisions will not be implemented until 2014.