That's the context without which such a statistic as in TFA is meaningless.
The other point to make is that the tax plan currently being debated in Congress does not give the middle class a tax break after netting out the proposal to do away with deductions for state and local taxes.
Great question! It turns out the top 20% earn about two-thirds of the income and pay about two-thirds of the total taxes (all taxes, not just federal income taxes). So all in all, it seems reasonable.
The other point to make is that the tax plan currently being debated in Congress does not give the middle class a tax break after netting out the proposal to do away with deductions for state and local taxes.