The economic recession and rising unemployment-plus changing demographics and baby boomers aging into Medicare-are among the factors expected to influence health spending during 2009-2019. In 2009 the health share of gross domestic product (GDP) is expected to have increased 1.1 percentage points to 17.3 percent-the largest single-year increase since 1960. Average public spending growth rates for hospital, physician and clinical services, and prescription drugs are expected to exceed private spending growth in the first four years of the projections. As a result, public spending is projected to account for more than half of all U.S. health care spending by 2012.