Growth in national health spending is projected to slow slightly from 6.9 percent in 2005 to 6.8 percent in 2006, marking the fourth consecutive year of a slowing trend. The health share of gross domestic product (GDP) is expected to hold steady in 2006 before resuming its historical upward trend, reaching 19.6 percent of GDP by 2016. Prescription drug spending growth is expected to accelerate to 6.5 percent in 2006. Medicare prescription drug coverage has dramatically changed the distribution of drug spending among payers, but the net effect on aggregate spending is anticipated to be small.