Johnston: Who Pays the Top Income Tax Rate?

Reuters:  Who Pays the Top Income Tax Rate?, by David Cay Johnston:

President Obama wants to raise the top marginal income tax rate on salaries and other ordinary income from 35% to 39.6% by letting the extended temporary Bush tax cuts expire at year-end. 

Mitt Romney wants to drop the top rate by a fifth to 28% (and running mate Paul Ryan has called for a top rate of 25%).

So who pays the 35% rate? How much do they pay? And how much more would they pay if the Clinton-era rate of 39.6% were restored?