It is my understanding that the wealth distribution pattern in the US overall follows Third World lines - massive concentration in the hands of the minority at the top, and very little amongst the large underclass. Two triangles, one standing on its tip. It is only natural that this sort of distribution leads to the top layers paying the majority of the taxes - even with a flat tax rate, they just plain have the most to tax while the multitudious destitute at the bottom of the heap simply don't have much anything that can be taxed.

That said, I'm not all that convinced this increase in revenues is due to the "wise fiscal policies of the current adminstration" so much as of general conjecturals of the economy - all governements and their supporters after all earnestly try to take the credit for good things and deflect the blame for bad ones, even when they didn't necessarily have anything to do with them.