The political debate over taxes often centers on income tax — a tax that gets increasingly larger for Americans who earn more money.

For example, every dollar you make under $9,275 is taxed at 10 percent — but every dollar you make over $415,050 is taxed at 39.6 percent. For obvious reasons, this type of tax is less popular with higher-income Americans.

But there are other federal taxes that Americans pay, too, the biggest of which are payroll taxes. Whether you earn $5,000 or $100,000, Americans pay up to 15.3 percent of their income to the government — largely to support Social Security and Medicare. (Some payroll taxes are levied on your employer, who is likely to pass down some or all of it to you. This is why the amount you are on the hook for is tough to pin down.) And income over $118,500 isn't subject to Social Security taxes, which means those who earn more start paying a smaller percentage of their income into payroll taxes.

Politicians don't spend much time debating the payroll taxes, and most of us don't spend much time thinking about them, either. In fact, most people don't even search the internet for the taxes on their pay stub called "Medicare" and "Social Security," which are payroll taxes.

Here's a chart that shows how the terms compare, in terms of Google search volume:

Payroll taxes don't factor into the political debate as much as income taxes, but they should: Most middle-class families pay more in payroll taxes than they do in income tax. Having an income tax–dominated debate presents a skewed picture of how all taxpayers fund the government. My colleague Dylan Matthews writes:

The taxes the privileged pay [end up] worthy of attention and the ones the poor pay are ignored. It paints a picture where the government is being supported on the backs of the wealthy, and the poor and middle class are free-riding. It leads to plans for various kinds of tax cuts and tax reforms that matter massively for the rich and very little for the poor.

That's why we charted out historical tax rates in the interactive above. You see that payroll taxes have been rising steadily while the top rates for income taxes have come down quite a bit. But as the search data shows, there just isn't much talk about the taxes that put the biggest burden on the middle class.

An earlier version of this story did not point out that income over $118,500 isn't subject to Social Security taxes.

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