One chart shows how out of control America's prescription-drug problem has become

In the debate over rising drug prices, pharmaceutical companies often defend themselves by saying prescription drugs only account for about 10% of healthcare spending. A new report from the Department of Health and Human Services says that's not the case. 

In fact, prescription drugs made up 16.7% of all healthcare spending in 2015, the government projects.

The report also breaks down some details on the pace at which prescription drug spending is increasing. Americans spent $457 billion on prescription drugs in 2015, up nearly $100 billion since 2009. And it's only going to keep rising. HHS expects prescription drugs to cost the US an estimated $535 billion by 2018.

The agency attributed the growth from 2010-14 partly to population growth and the increase in numbers of prescriptions. 

But it's also pretty clear that prices are a big factor, and HHS nailed that with a chart showing how fast revenue for retail prescription drugs has increased since 2009, compared with how many prescriptions were filled.

 Department of Health and Human Services

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