A new survey on health care finds that a small percentage of very sick patients account for about half of all medical spending and are the driving force behind double-digit increases in insurance premiums, the National Journal reports.

The survey, by the non-partisan National Institute for Health Care Management Foundation, found that from 2005 to 2009, 5% accounted for 47.5% of all health care spending, and 1% were responsible for 20% of all medical costs. Half the population racks up only 3% of total spending.

In 2008, the average person's medical costs were about $233. For the top 1%, the average was $76,476.

Read the full report here.