Health care spending in the U.S. reached $2.2 trillion in 2006, according to estimates by Blue Cross Blue Shield Association, Chicago.

That figure represents 16.5% of the nation’s gross domestic product and could reach 20% by 2015, according to BCBS calculations.

The government remains the largest payer for health care, bearing almost half the total costs, primarily through public programs such as Medicare and Medicaid. Private health insurance accounts for about one-third of the total, according to the Blues.

About 68.6% of the U.S. population is covered by private health insurance–59.5% by employer-based private insurance and 9.1% by direct-purchase private insurance.

These and other data are included in the association’s 2007 Medical Cost Reference Guide, which also covers topics such as health care utilization, chronic disease and obesity and trends among hospitals, physicians, consumers and the uninsured. The guide is available online at Document Link