in that the rich get a bigger piece of the overall pie. But Democratic results make the economic pie bigger. So a smaller piece of a bigger pie may be larger in absolute terms than a bigger piece of a smaller pie.

Was that confusing? In college, we called this pizza math. Back then a large pizza cost about as much as two small pizzas. With the small pizzas, you could eat more pieces, but each piece was a lot smaller than a single slice from a large pie. When you include the crust factor, the large was more economical. Eventually, after much calculation and price comparison between pizzerias, we decided the mathematically correct answer was pan pizza, because the toppings go all the way to the edge, and some of us tended to throw unadorned crust in the trash.

(Edited to add: During this period, Republicans held the White House for 40 years. So the 2.2% differential, compounded over 40 years gives a GDP 2.2 times larger. (Man, we would have gotten a whole free pizza out of that!) The rich would definitely be richer if the economy grew at the Democratic rate rather than the Republican rate.)