On December 18, 2008, the Congressional Budget Office (CBO) released a major report entitled “Budget Options, Volume 1: Health Care,” which sets forth 115 policy options for Congress to consider as it addresses health care system reform. The CBO points out that Medicare is expected to grow from 2.8 percent of gross domestic product (GDP) in 2008 to nearly 9 percent of GDP in 2050. This spending growth will be fueled primarily by growth in per capita medical costs, according to the CBO, with the aging of the population playing a secondary role. In light of these trends, the CBO offers specific options addressing such areas as: health insurance (market reforms, tax treatment, access to federal programs); health care quality and efficiency; geographic variation in Medicare spending; paying for Medicare services (including hospital, physician, imaging, and post-acute care, and Medicare Advantage plan services, among others); financing and paying for services in Medicaid (including drug payment revisions) and SCHIP; premiums and cost sharing in federal health programs; long-term care; health behavior and health promotion; and closing the gap between Medicare’s spending and receipts. The CBO also issued a separate report focusing on insurance reform, “Key Issues in Analyzing Major Health Insurance Proposals.” The CBO warns that without changes in policy, a substantial and growing number of nonelderly people are likely to be without health insurance. This issue cannot be addressed without making major changes in the financing or provision of health insurance and health care, which will involve "difficult trade-offs between the objectives of expanding insurance coverage and controlling both federal and total costs for health care." The report describes the assumptions that CBO would use in estimating the effects of key elements of proposals to modify the health insurance system on federal costs, insurance coverage, and other outcomes. In particular, it considers the types of issues that would arise in estimating the effects of proposals to: provide tax credits or other types of subsidies to make insurance less expensive to the purchaser; require individuals to purchase health insurance; require firms to offer health insurance to their workers or pay into a fund that subsidizes insurance purchases; replace employment-based coverage with new purchasing arrangements or provide strong incentives for people to shift toward individually purchased coverage; and provide individuals with coverage under, or access to, existing insurance plans such as the Medicare program, either as an additional option or under a “Medicare-for-all” single-payer arrangement.